yi_n_n__rL_n_ 


REESE  LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA 


Deceived 
Accession  No.       91390.   Class  No. 


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The  National  Ammonia  Go. 

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MANUFACTURERS  OF  ABSOLUTELY   PURE  AND  DRY 


Liquid 

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Ammonia 


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For  Refrigerating  and  Ice  Making  Purposes. 

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UNEXCELLED  GOODS.  UNEQUALED  SERVICE 

Our  Ammonia  can  be  had  of  the  Following: 

NEW  YORK—  PITTSBURGH— 

The  De  La  Vergne  Ref.  Mach.  Co.  Union  Storage  Co.,  Transfer  Agts. 


W.  M.  Schwenker. 


NEW   ORLEANS— 


The  National  Ammonia  Co.,  L  N   Brimswi*  *  m 


1OP    .IT    T)nv:n  r»n   n  * 

Theo.  J.  Goldschmid  Co.  ™  W'  Davis  O11  Co- 

BALTIMORE-Wm.  Mitchell.  T  MaUinckrodt  Chemical  Work, 

WILMINGTON—  Larkin  &  Scheffer. 

Delaware  Chemical  Co.  CHICAGO  - 

BUFFALO-S.  J.  Krull.  A.  Magnus'  Sons'  Co 

BOSTON—  Fuller  &  Fuller  Co  ' 

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' 


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INDIANAPOLIS,  IND.—  SYDNEY,  N.  S.  W. 

Indianapolis  Warehouse  Co.  The  Ammonia  Co.  of  Australia. 


ADVERTISEMENTS 


CROSBY 


STEAM  GAGE  AND 
VALVE  CO. 


SOLE  MANUFACTURI 


CROSBY  STEAM   ENGINE 

AND 

AMMONIA  INDICATOR 

Approved  and  adopted  by  the  U.  S.  Govern- 
ment. It  is  the  standard  in  nearly  all  the  great 
Hlectric  Light  and  Power  Stations  of  the  United 
States.  It  is  also  the  standard  in  the  principal 
Navies,  Government  Ship  Yards  and  the  most 
eminent  Technical  Schools  of  the  world. 

When  required  it  js  furnished  with  Sar- 
gent's Eleetrieal  Attachment,  by  which  any 
number  of  diagrams  from  Compound  Engines 
can  be  taken  simultaneously. 

This  attachment  is  protected  by  Letters 
Patent.  The  public  is  warned  against  other 
similar  attachments  which  are  infringements. 


ALSO  SOLE  MANUFACTURERS   OF 


Perfect  in  Design. 
Faultless  in  Work- 
manship. 


Crosby  Improved  Steam  Gages,  Pop  Safety  Valves,  Water  Relief  Valves, 

Patent    Gage  Testers,    Safe  Water   Gages,   Revolution  Counters, 

ORIGINAL  Single  Bell  Chime  Whistles  and  other  standard 

specialties  used  on  Boilers,  Engines,  Pumps,  etc. 

MAIN  OFFICE  AND  WORKS:  BOSTON,  MASS.,  U.  S.  A. 

Stores:  BOSTON,  NEW  YORK,  CHICAGO  and  LONDON,  ENG. 


COILS 

BENDS  AND  MANIFOLDS  FOB 

Ice  and  Refrigerating  Machinery 

AMMONIA  VALVES  AND  FITTINGS. 

Hairisburo 
Pipe  Bending  Go.,  w. 

HARRISBURG,   PA. 

The  Harrisburg  Copper  Coil 
Feed  Water  Heater. 


CARBONIC  ACID   GAS   AND   ANHYDROUS 
AMMONIA 

RECEIVERS  AND  CYLINDERS 


INDICATING 


TtiE 


REFRIGERATING  MACHINE 


THE   APPLICATION    OF   THE   INDICATOR    TO   THE   AMMONIA 

COMPRESSOR   AND   STEAM    ENGINE,  WITH    PRACTICAL 

INSTRUCTIONS  RELATING  TO  THE  CONSTRUCTION 

AND  USE   OF   THE  INDICATOR   AND  READING 

AND    COMPUTING  INDICATOR    CARDS 


BY 

GARDNER  T.  VOORHEES,  S.  B. 

MECHANICAL    ENGINEER    WITH    THE 

QUINCY   MARKET   COLD  STORAGE   CO. 

BOSTON,  MASS. 


CHICAGO 

H.  S.  RICH  &   Co. 


Copyrighted  1898,  by  H.  S.  RICH  &  CO. 

ALL    RIGHTS   RESERVED. 


Press  of 
ICH  AND  REFRIGERATION, 

CHICAGO. 


PREFACE. 

Often  while  plotting-  the  adiabatic  curve  on 
an  indicator  card  taken  from  an  ammonia  com- 
pressor, I  have  wished  to  shorten  the  time  re- 
quired and  simplify  the  process.  This  led  to 
working-  out  the  constants  in  Table  No.  1.  Having- 
these  constants,  Table  No.  2  naturally  sug-g-ested 
itself  to  still  further  simplify  the  work.  In  addi- 
tion to  this  I  have  added  such  other  matter  as 
seemed  pertinent  to  a  work  of  this  character, 
hoping-  to  place  before  the  reader  all  necessary 
references  for  one  who  may  have  to  work  up 
indicator  cards  taken  from  an  ammonia  com- 
pressor. If  my  reader  appreciates  the  value  of 
the  adiabatic  curve  after  looking-  throug-h  this 
work,  and  learns  to  use  Table  No.  2,  I  feel  that 
my  aim  will  have  hit  the  mark. 

G.  T.  V. 


91390 


CONTENTS. 


PART  I. 

INDICATING  THE   AMMONIA  COMPRESSOR. 

Chapter          I.— The   Elementary  Indicator;  a  simple 

description  of  the  principles  involved     7 
Chapter        II. — The  Value  of  Indicating- a  Compressor  11 

Chapter      III.— The  Adiabatic  Curve 19 

Chapter       IV.— The  Isothermal  Curve 25 

Chapter         V. — Discussion  of  the  Adiabatic  and  Iso- 
thermal Curves 29 

Chapter       VI. — Finding  the  Horse  Power  of  an  Indi- 
cator Card 37 

Chapter  VII. — Actual  Displacement  of  a  Compressor  39 
Chapter  VIII.— Special  Faults  as  Shown  by  Cards. .  .  4<i 
Chapter  IX. — Wet  Compressor  System  Indicating-. .  51 
Chapter  X. — Instructions  for  Connecting-  Indicator 

to  Machine..  .  57 


Chapter 
Chapter 

Chapter 
Chapter 
Chapter 
Chapter 
Chapter 


PART  II. 

INDICATING    THE   STEAM    ENGINE. 

I. — The  Steam  Engine  Indicator 59 

II.— How   and  Where  to  Attach  the  Indi- 
cator   72 

III.— The  Drum  Motion 

IV. — How  to  Take  Diagrams 

V. — How  to  Find  the  Power  of  an  Engine. 

VI.— The  Hyperbolic  Curve 

VII.—  Amsler's  Polar  Planimeter. . , 


76 

84 

89 

96 

103 


Chapter 
Chapter 


PART  III. 

CONSTRUCTION   OF    INDICATORS. 

I.— The  Crosby  Indicator 108 

II.— The    Bachelder    Adjustable     Spring 

Indicator..,  ..116 


CONTENTS.  V 

Chapter      III. — Improved  Robertson-Thompson   Indi- 
cator  119 

Chapter       IV.— The  Buffalo  Indicator. 123 

Chapter        V. — American  Thompson.  Indicator 126 

Chapter       VI.— The  Tabor  Indicator 133 

Chapter     VII. — The  Improved  Victor  Reducing  Wheel.  141 

Chapter  VIII.— The  Ideal  Reducing-  Wheel .144 

Chapter       IX.  —  Sargent's  Electrical  Attachment  for 

Steam  Engine  Indicators 146 

Chapter        X. — Armsler's  Polar  Planimeter 149 

Chapter       XI.— The  Lippincott  Planimeter 150 

Chapter     XII.— The  Coffin  Averaging  Instrument 154 

PART  IV. 

MISCELLANEOUS   TABLES. 

Properties  of  Saturated  Ammonia 160-163 

Table  of  Ammonia  Gas  (Super-heated  Vapor) 164 

Refrigerating  Effect  of  One  Cubic  Foot  of  Ammonia 

Gas 165 

Number  of   Cubic  Feet  of  Gas  Pumped  per  Minute  to 

Ton  of  Refrigeration 165 

Anhydrous  Ammonia,  Composition  of 166 

Testing  Anhydrous  Ammonia 166-167 

Comparisons  of  Thermometer  Scales 168 

Mean  Pressure  of  Diagram  of  Ammonia  Compressor .  169 

Properties  of  Saturated  Steam , 170-172 

Mean  Effective  Pressure  of  Diagram  of  Steam  Cyl- 
inder  173 

Head  of   Water  and  Equivalent  Pressure  in  Pounds 

per  Square  Inch 174 

Properties  of  Solution  of  Salt  (Chloride  of  Sodium). .  .175 

Properties  of  Solution  of  Chloride  of  Calcium 175 

Diameters,  Areas  and  Circumferences  of  Circles.  .176-178 
Table  of  Piston  Speeds  :  Feet  per  Minute 179 


INDICATING 

THE 

REFRIGERATING    MACHINE 


PART  I. 
INDICATING  THE  AMMONIA  COMPRESSOR. 


CHAPTER  I. 

THE    ELEMENTARY   INDICATOR. 

For  the  convenience  of  those  who  are  not 
familiar  with  the  principle  of  the  indicator,  but 
may  wish  to  look  through  this  book,  I  will  give 
an  elementary  description  of  the  principles  in- 
volved. I  sincerely  hope  that  thus  I  may  be  able 
to  bring-  this  work  understandingly  before  those 
who  are  interested  in  or  own  compressors,  but 
who  have  not  had  a  technical  education. 

In  Fig.  Itf,  shown  on  opposite  page,  let  A  be 
the  compressor  cylinder;  B  the  piston;  C  the 
suction  valve;  D  the  discharge  valve;  E  the 
piston  rod;  F  the  cross-head;  G  G  cross-head 
guides;  If  a.  board  made  fast  to  the  cross-head; 
/a  piece  of  paper  called  an  indicator  card  blank, 
which  is  tacked  to  board  H;  /a  small  cylinder, 
having  piston  A" and  piston  rod  Z,  compression 
spring  M;  Arpencil  carried  by  piston  rod  L;  O  O 
pipe  leading  from  cylinder  A  to  cylinder  J;  P 
cock  that  may  connect  cylinders  A  and/,  or  shut 
off  A  from  /  at  the  same  time  leaving  cylinder/ 
open  to  the  atmospheric  pressure. 


8  INDICATING    THE 

Now  we  will  suppose  pencil  Arto  press  against 
paper  /,  and  cross-head  f^to  move  in  the  direc- 
tion 1,  2.  Evidently  the  pencil  N  will  trace  the 
straight  line  aa^  on  paper  /.  Now  whatever 
pressure  exists  in  cylinder  A  must  also  be  in 
cylinder  J,  being  transmitted  through  the  pipe 
O  O.  Suppose  now  the  pencil  N  at  position  c 
representing  atmospheric  pressure  in  cylinder 
A,  then  allow  pressure  in  cylinder  A  to  gradually 
increase,  the  cross-head  F  remaining  fixed  in 
position.  It  is  evident  that  this  pressure  will 
move  piston  K,  compress  spring  J/and  trace  the 
line  cb  with  pencil  N.  Then  if  the  pressure  in 
cylinder  A  is  reduced  the  piston  It  will  return 
to  its  original  position  by  virtue  of  spring  M. 
Now  suppose  spring  Mto  be  so  constructed  that 
one  pound  per  square  inch  pressure  in  cylinder 
A  will  compress  it  .01  of  an  inch  and  that  100 
pounds  per  square  inch  will  compress  it  one  inch; 
it  will  be  evident  that  every  .01  of  an  inch  of  line 
a  b  represents  one  pound  per  square  inch  press- 
ure in  cylinder  A.  If  a  b  is  .75  inches  long, 
then  the  pressure  in  cylinder  A  is  seventy-five 
pounds. 

If  cock  P  is  so  turned  as  to  open  cylinder/ 
to  the  air,  when  the  cross-head  F  moves,  it  will 
cause  pencil  N  to  trace  line  c  c^ ,  called  the  atmos- 
pheric line.  All  vertical  distances  above  this 
line  will  represent  pressures  above  the  atmos- 
phere. All  vertical  distances  below  this  line 
will  represent  pressures  below  the  atmosphere. 
The  pressure  of  the  atmosphere  is  14.7  pounds 
per  square  inch.  Should  a  perfect  vacuum  be 
found  in  cylinder  A,  then  pencil  N  would  go  to 
#!,#!  representing  to  scale,  by  its  vertical  dis- 


AMMONIA    COMPRESSOR.  H 

tances  from  line  c  c\ ,  14.7  pounds  per  square  inch 
pressure.  Now  it  should  be  clear  that  any  varia- 
tion of  pressure  in  cylinder  A  will  either  raise  or 
lower  pencil  N  in"  relation  to  line  c  cl ,  and  that  any 
motion  of  the  cross-head  F  will  move  the  paper 
so  that  the  pencil  A^will  vary  its  horizontal  dis- 
tance from  line  bb^.  As  the  cross-head  Amoves 
with  the  same  motion  as  that  of  piston  B  it  is 
evident  that  all  points  at  a  horizontal  distance 
from  line  b  b1  represent  different  positions  of  pis- 
ton B,  and  all  vertical  distances  from  line  ccl 
represent  pressures  in  cylinder  A  on  piston  B 
at  these  positions. 

Now  let  us  see  how  the  indicator  pencil  will 
act  under  an  actual  test.  Let  us  suppose  that 
piston  B  has  just  started  in  the  direction  of  the 
full  arrow.  Then  pencil  N  at  point  a  shows 
the  beginning-  of  piston's  stroke  and  pressure, 
ca,  which  is  the  back  pressure  (gauge).  As  the 
piston  B  moves  forward  the  gas  flows  into  cyl- 
inder A  through  suction  valve  C  at  the  con- 
stant back  pressure  from  the  expansion  cham- 
ber through  pipe  R,  and  the  pencil  traces  the 
line  a ai. 

Now  the  piston  B  having  reached  the  end 
of  its  stroke,  B^  starts  back  in  the  direction  of 
the  dotted  arrow.  In  doing  this  it  begins  to. 
compress  the  gas  in  the  cylinder  ^4,  thus  clos- 
ing suction  valve  C;  and  as  the  pressure  in  cyl- 
inder A  becomes  more  and  more,  the  pencil 
traces  the  curved  line  a±  d  (the  compression,, 
curve).  When  the  piston  reaches  the  position, 
Z?2»  corresponding  with  the  pencil  point  d,  the. 
pressure  in  cylinder  A  is  a  little  greater  than 
that  transmitted  by  pipe  Q  from  condenser  to 

(2) 


10  INDICATING    THK 

the  discharge  valve  D.  From  this  position  the 
piston  discharges  the  gas  past  the  discharge 
valve  to  the  end  of  the  stroke,  the  pencil  in 
the  meanwhile  tracing  the  wavy,  peaked  line, 
db.  The  reason  for  the  unevenness  of  this  line 
is  the  chattering  of  the  discharge  valve  D. 
The  piston  B  now  having  reached  its  original 
position,  starts  to  go  back  in  the  other  direction 
(that  of  the  full  arrow)  again.  Now  the  dis- 
charge valve  D  closes,  due  to  the  condenser 
pressure,  and  the  pressure  in  cylinder  A  falls  to 
that  due  to  the  suction  or  back  pressure.  As  this 
change  takes  place  while  the  piston^ is  changing 
its  motion  from  forward  to  backward,  the  cross- 
head  moves  only  a  very  small  amount,  and  a  nearly 
vertical  line,  b  a,  is  traced  by  the  pencil  N. 

We  have  now  followed  the  pencil  through 
rts  travels,  and  the  resulting  diagram,  aaldb 
a,  is  the  desired  indicator  diagram.  This  same 
explanation  can  apply  to  a  steam  card  by  going 
around  the  diagram  the  other  way;  bdal  ab  will 
be  a  steam  engine  card,  except  that  the  line  bd  will 
be  more  smooth,  the  line  da^  will  represent  the 
expansion  line,  d  the  point  of  cut-off,  and  a1  a 
the  exhaust  line.  The  practical  forms  of  indi- 
cators, such  as  are  used  to-day,  do  not  differ 
in  principle  from  this  elementary  form;  they 
differ  only  in  detail.  The  card  /  is  carried  on 
an  oscillating  drum, which  is  oscillated  by  a  cord 
from  the  cross-head.  The  pencil  is  carried  by  a 
straight  line  multiplying  device.  Another  chap- 
ter gives  full  description  of  the  various  standard 
makes  of  indicators,  so  I  will  not  go  farther  into 
the  subject  of  the  construction  of  the  indicator 
at  this  point. 


AMMONIA    COMPRESSOR.  11 

CHAPTER  II. 

THE  VALUE  OF  INDICATING  A  COMPRESSOR. 

In  this  chapter  I  will  try  to  demonstrate  the 
value  of  indicating"  an  ammonia  compressor,  of 
doing-  it  regularly,  and  knowing- how  to  correctly 
interpret  the  meaning-  of  the  indicator  card.  I 
have  known  men  who  were  well  up  on  indicator 
practice,  and  who  are  intellig-ent  engineers,  to 
let  a  compressor  run  for  months,  when  a  very 
little  knowledg-e  of  such  methods  as  I  hope  to  set 
forth  would  have  saved  a  great  amount  of  worry 
in  regard  to  the  quality  of  work  being-  done,  and 
a  good  many  hundred  dollars  of  expense  on  coal 
bills. 

All  competent  engineers  know  the  names  of 
the  various  lines  and  are  familiar  with  the  gen- 
eral  appearance  of  the  indicator  card.  They 
know  that  the  admission  line  is  parallel  to  the 
atmospheric  line.  The  compression  line  rises 
in  an  easy  curve  to  the  discharg-e  line.  The 
discharge  line  is  usually  wavy  or  peaked,  due  to 
the  vibration  of  the  discharge  valves.  The  ad- 
mission and  discharge  lines  should  be  joined  by 
a  nearly  vertical  line.  The  card  should  have  a 
square  heel.  We  know  that  this  square  heel  in- 
dicates the  amount  of  clearance. 

In  Fig.  1  the  card  has  a  square  heel  at  «,  con- 
sequently you  say,  "  The  clearance  is  small." 
If  the  card  had  been  like  Fig.  2,  you  would  say, 
u  Very  bad;  too  much  clearance,"  and  you  would 
overhaul  your  compressor  and  make  the  clear- 
ance what  it  should  be.  How  many  engineers 


12 


INDICATING    THK 


AMMONIA    COMPRESSOR. 


13 


14 


INDICATING     THE 


AMMONIA    COMPRESSOR.  15 

go  any  farther  than  this?  They  take  a  card  like 
Fig-.  1,  look  at  it,  see  that  it  has  a  good  square 
heel,  and  say,  u  This  is  a  good  card."  As  a  re- 
sult they  g-o  back  to  their  other  duties,  thinking 
that  their  compressor  is  doing-  g-ood  work.  Here 
is  where  many  a  good  man  makes  a  mistake. 
He  has  done  what  he  could,  but  for  lack  of  a 
practical  way  of  applying  thermodynamic  reason- 
ing to  his  card  he  can  go  no  farther. 

I  am  acquainted  with  an  engineer  who  knows 
a  great  deal  about  running  a  compression  plant. 
One  day  he  handed  me  a  card  like  Fig.  3.  He 
said,  "Here  is  a  good  card."  I  took  the  card, 
applied  the  simple  rules  to  it,  that  I  am  about  to 
give,  and  found  that  the  compressor  was  in  a  very 
bad  way.  I  doubt  if  there  is  an  engineer  who 
can  look  at  the  card  as  given  in  Fig.  3,  and  say  it 
is  a  good  or  a  bad  card.  It  is  impossible  to  tell 
whether  the  compression  line  is  good  or  bad  by 
a  simple  inspection.  One  may  notice  if  the  com- 
pression line  is  very  bad.  Even  then  I  think 
there  would  not  be  one  man  in  a  great  many  that 
could  pass  a  valuable  opinion  on  it. 

What  the  engineer  needs  is  a  guide,  some- 
thing to  compare  his  card  with;  something  that 
he  knows  is  all  right.  In  a  picture  or  diagram 
the  way  of  comparing  size  and  proportion  is  by 
having  some  familiar  object,  as  a  man,  for  com- 
parison. You  may  know  then  that  the  bridge 
you  are  looking  at  is  large  or  small,  that  you  are 
looking  at  the  picture  of  a  great  cathedral  or  a 
small  church.  In  much  the  same  way  it  is 
necessary  to  have  your  comparison  on  an  indi- 
cator card. 

This   comparison   or  guide   is   the  adiabatic 


16 


INDICATING    THI<; 


AMMONIA    COMPRESSOR.  17 

line.  The  isothermal  line  is  interesting-,  and 
also  serves  as  a  guide,  but  it  is  a  poor  guide. 
One  cannot  draw  sound  conclusions  in  all  cases 
from  the  isothermal  line's  relation  to  the  com- 
pression curve,  as  traced  by  the  indicator  pencil. 
The  adiabatic  line  is  the  true  guide.  The  cal- 
culation of  this  adiabatic  line  necessitates  the 
use  of  logarithms  in  calculating  the  fractional 
powers  of  numbers.  This  may  be  difficult  for 
some  engineers  to  do.  Even  our  best  engineers 
will  find  that  it  is  no  small  matter  to  figure 
the  adiabatic  line  for  an  indicator  card.  They 
can  do  it  easily  enough,  no  doubt,  but  it  will  take 
much  more  valuable  time  than  they  usually  have 
to  devote  to  it.  Consequently,  I  believe  that  if  I 
set  forth  a  simple  and  practical  way  of  obtaining 
this  line,  engineers  will,  by  using  this  method, 
be  able  to  get  much  better  work  out  of  their 
machines.  The  owners  of  plants  will  also  save 
money  that  is  needlessly  wasted  at  present. 

I  reproduce  Fig.  3  here  in  Fig.  4,  having 
drawn  the  adiabatic  line  a  a  on  the  card.  This 
card,  that  looked  so  good  to  my  friend  the  engi- 
neer, is  now  shown  to  be  very  bad.  I  told  him 
that  probably  the  cylinder  gasket  between  the 
discharge  port  and  the  cylinder  was  blown  out. 
(The  reasoning  for  this  will  be  given  later.) 
Upon  an  examination  of  the  compressor  this  was 
found  to  be  the  case.  The  machine,  I  am  sorry 
to  say,  had  been  running  for  a  long  time  in  this 
condition.  Being  a  large  machine,  it  had  need- 
lessly wasted  a  good  deal  of  money  while  thus 
running. 


18 


INDICATING    THE 


AMMONIA    COMPRESSOR  19 


CHAPTER  III. 

THE    ADIABATIC    CURVK. 

An  adiabatic  line  is  a  curve  that  represents 
the  adiabatic  expansion  or  compression  of  a  gas 
or  vapor.  Adiabatic  expansion  or  compression 
is  the  expansion  or  compression  of  a  gas  or 
vapor,  without  loss  or  gain  of  heat.  It  is 

Op  Op 

expressed  by  pv^'^=pl'vl^  where  p  =  initial 
pressure,  v=  initial  volume,  p^  =  final  pressure, 
27 !  =  final  volume,  £p=  specific  heat  at  constant 
pressure,  £v  =  specific  heat  at  constant  volume. 
cj-  is  called  the  ratio  of  specific  heats;  for  am- 
monia gas  it  is  .3^°^  =  1.3  .*.  p  v1-'3  =plvl*-*. 
That  is,  the  initial  pressure  times  the  1.3  power 
of  the  initial  volume  is  equal  to  the  final  press- 
ure times  the  1.3  power  of  the  final  volume,  p 
and^j  being  absolute  pressures. 

In  Fig.  5  the  atmospheric  line  A  A  is  the  line 
drawn  by  the  indicator  pencil  when  the  indicator 
cock  is  so  turned  that  the  atmospheric  pressure 
is  on  both  sides  of  the  indicator  piston.  Meas- 
ure off  perpendicular  to  and  below  A  A  the  dis- 
tance a  b,  equal  to  the  atmospheric  press- 
ure, 14.7  pounds,  using  the  same  scale  as  that  of 
the  indicator  spring.  Draw  a  line  through  b 
parallel  to  A  A.  This  line  is  the  vacuum  line 
V  V.  Draw  lines  Z?..Z?and  C  C,  perpendicular  to 
the  atmospheric  line  A  A,  and  tangent  to  or 
touching  the  extreme  right  and  left  hand  por- 
tions of  the  diagram.  I  disregard  the  clearance, 
as  being  too  small  to  appreciably  affect  the  re- 
sults to  be  obtained.  All  pressures  must  be 


20  INDICATING    THE 

measured  at  right  angles  from  the  vacuum  line 
VV.  The  pressures  are  then  the  true  or  abso- 
lute pressures. 

Now  divide  line  V  V  into  ten  equal  parts. 
The  point  where  the  right  hand  end  of  the  dia- 
gram cuts  the  line  C  C  at  c  is  the  point  of  the 
beginning  of  the  compression.  The  vertical 
distance  from  c  to  V  V  is  the  absolute  back 
pressure  when  measured  on  the  same  scale  as 
that  of  the  indicator  spring. 

Let  p=  the  absolute  back  pressure,  as 
measured  from  the  vacuum  line  V  V  to  c.  At 
the  beginning  of  the  compression,  as  the  cylin- 
der is  full  of  gas,  z'  can  be  called  1.  The  most 
convenient  point  from  which  to  draw  the  adia- 
batic  line  will  be  from  the  point  of  the  begin- 
ning of  compression,  or  where  v=l.  Now  as 
I1-3  =  1,  we  have  /X  1  =/,  z^1  3  or  p^  =  ^3. 
pi  is  the  ordinate  (or  vertical  distance  from 
VV)  of  any  point,  F,,  on  the  adiabatic  line  for 
a  corresponding  abscissa  (or  horizontal  distance 
on  V  Ffrom  C  C1),  p  being  the  absolute  back 
pressure  under  consideration,  and  z1,  varying 
from  1  to  0. 

The  divisions  of  V  V  are  now  marked,  as 
shown  on  Fig.  5,  viz.:  .9,  .8,  .7,  .6,  .5,  .4,  .3,  .2,  .1 
and  0.  These  points  on  V  V  indicating  that 
the  volume  at  these  points  is  either  .9,  .8,  .7  to 
.1  or  0,  as  the  case  may  be. 

.I1<3=the  number  which=l. 3 X logarithm  of  .1. 
Log".  .1=9.000000—10 

1.3        multiply  by  1.3 
11.700000—13 

—3  +3  add  and  subtract  3 

8.700000— 10=lojr.  of  .05 
.-.       .OS=.l1'3 


AMMONIA    COMPRESSOR.  21 

Log".  .2=9.301030—10 

1.3     multiply  by  1.3 
27903090 
9301030 


12.0913390—13 

—3  _  -j-3     add  and  subtract  3 
9.0913390—  10=log-  of  .123 
.-.     .123=.2I<8 

In  like  manner: 

TABLE  No.  1. 
.I1'3  =3.050 
.2l'3=.123 
.31's=.209 
.41-3=.304 
.5'-s=.406 


Now,  having-  the  values  of  .I1  3  to.91  3  we  can 
find  values  for  p  .^  p  .%•>  p  .%  to^.9,  by  substituting 
the  corresponding-  values  of  v^  ,  v  ,2  to  v,9  in  for- 


P 


t-»=^ 

p-=  -£* 

P  6=:  ~5v^ 

As  =  -=- T7 


A3=-^4 

A.=  li 
# 


22 


INDICATING    THE 


TABLE  NO.  2. 

ADIABATIC    CONSTANTS. 


l>> 

15 

16 

17          IS          19         540         »l         •&£ 

its 

£4 

P-! 

17  2 

18.4 

19.5     20  6     21.8     22.9     24.1     25.2 

264 

27.6 

P.* 

20.0 

21.4 

22.7     24.3     25.4     26.7     28.1     29.4 

30.7 

32.1 

P.  7 

24.9 

25.4 

27.0 

28.61     30.2     31.8     33.4     35.0 

36.5 

38.1 

l'.( 

29.2 

31.1 

33.1 

35.0     36.9     38.6     40.8;    42.8 

44.7 

46.7 

P.r, 

37.0 

39.5     41.8 

44.4     46.8;    49.3     51.8     54.3 

56.7 

59.2 

P.  4 

49.3 

52.7     56.8 

59.2     62.5!    65.8     69.ll     72.4 

75.7 

79.0 

P.3 

71.7 

76.5     81.3 

86.1 

90.8;     95.6   100.3'  105.2 

110.0 

114.8 

I1.  2 

122.0 

130.0  138.2 

146.3 

154.5   162.7   170.6 

178.9 

187.U 

196.1 

P.. 

300.0 

320.0  340.0 

360.  0 

380.0;  400.0  420.0 

440.0 

460.0 

480.0 

l>. 

*5 

26 

x7 

*8 

*» 

30 

31 

tut 

»3 

34 

P-  8 

28.7 

29.8 

31.0 

32.1 

33.2 

34.4 

35.6 

36.7 

37.9     39.0 

I'-  » 

33.4 

34.7 

36.1 

37.4 

38.8 

4<U 

41.4 

42.8 

44.1     45.4 

P'7 

39.7 

41.3 

42.8 

44.5 

46.2 

47.7 

49.3 

50.8 

52.4i    54.0 

P'« 

48.7 

50.6 

52.5 

54.4 

56.4 

58.3 

60.3 

62.2 

64.2:     66.2 

N 

61.7 

64.2 

66.6 

69.1 

71.5 

74.0 

76.4 

78.8 

81.  4|    83.8 

P-» 

82.3 

85.5 

88.8 

92.2]     95.4 

98.5 

102.0 

105.2 

108.6'  111.8 

P  :. 

119.6 

124.2 

129.0 

133.9   138.7 

143.4 

148.2 

153.0 

157.8  162.5 

p.;, 

203.2 

211.4 

219.4 

227.8   235.8 

244.0 

252.0 

260.0 

268.2!  276.3 

p.i 

500.0 

520.0 

540.0 

560.0   580.0J  600.0 

620.0 

640.0 

6HO.O|  680.0 

!>' 

35 

30 

37 

3»         39     1     40 

41 

4«          43 

44 

P-;, 

40.2 

41.3 

42.5 

43.6     44.71     45.9 

47.1 

48.21     49.3 

50.5 

P-H 

46.8 

48.1 

49.4 

50.8     52.1!    53.4 

548 

56.1 

57.4 

58.8 

P-7 

55.6 

57.2 

58.8 

60.4     62  0     63.6 

65.2 

66.7 

68.3 

69.8 

I'M; 

68.0 

70.0 

71.9 

73.8     75.8     77  8 

79.7 

81.6 

83.6 

85.5 

P-H 

86.3 

88.7 

91.2 

93.7     96.2     98.7 

101.0 

103.5 

106.0 

108.3 

PM 

115.1 

118.4 

121.7 

125.0!  128  2   131.6 

185.0 

138.1 

141.6 

144.7 

P-a 

167.3 

172.1 

177.0 

181.H 

186.5 

191.2 

196.0 

200.8 

205.8 

213.0 

|»., 

284.7 

292.7 

300.7 

309.0 

317.  (i 

325.0 

333.4 

341.2   349.2 

357.8 

I'-i 

7000 

7200 

740.0 

760.0 

780.0   800.0 

820.0 

840  0,  8600 

880.0 

!>• 

45 

46 

47 

4* 

49 

50 

51 

5* 

53 

54 

P'8 

51.7 

52.7 

539 

55.1 

56.2 

57.4 

58.5 

59.7 

60.8 

62.0 

I'-H 

60.2 

61.5 

62.8 

64.1 

65.4 

66.8 

68.1 

69.4 

70.8 

72.1 

P-7 

71.5 

73.1 

74.7 

76.3 

77.8 

79.5 

81.0 

82.6 

84.2 

85.8 

!>.« 

87.5 

89.4 

914 

93.3 

95.2 

97.2 

99.1 

101.0 

103.0 

105.0 

P..-, 

110.8 

113.2 

115.8 

118.2 

120.5 

123.0 

125.6 

128.0 

130.6 

138.0 

P-  1 

148.0 

1513 

154.6 

158.0 

161.2 

164.5 

167.7 

171.0 

174.3 

177.6 

P-:t 

215.0 

220.0 

224.8 

229.5 

234.2 

239.0 

243.8 

248.6 

253.5 

258.1 

P-2 

366.0 

3740 

382.0 

390.0 

398.0 

407.0 

414.0 

422.0 

432.0 

438.0 

P., 

900.0 

920.0  940.0 

960.0 

980.0 

1000.0 

1020.0 

1040.0 

1060.0 

1080.0 

!»• 

55 

56 

57 

58 

59 

60 

j 

!'•« 

63.2 

64.3 

65.4 

666 

67.7 

68.8 

P-  8 

73.5 

74.8 

76.1 

77.5 

78.8 

80.1 

P-7 

82.4 

89.0 

90.5 

92.2 

93.7 

95.3 

i 

P-G 

107.0 

10S.9 

110.8 

112.8 

114.8 

116.8' 

P-r, 

135.5 

138.0 

140.4   142.8 

145.2 

147.7 

P.I 

181.0 

184.2 

187.5 

190.7 

194.0 

197.3 

P.  3 

263.0 

267.8 

272.4 

277.2 

282.0 

287.0 

P.  2 

447.0 

466.0 

461.0 

472.0 

480.0 

487.0 

P-. 

1100.0 

1120.0 

1140.01160.0 

1180.0 

1200.0 

AMMONIA    COMPRKSSOK.  23 

If  now  we  give  a  value  of  15  to  p= fifteen 
pounds  absolute  back  pressure,  and  substitute 
for  z>.91>3  to  z*.!1'3  their  values  as  given  in  table 
No.  1  we  will  have : 

A«  =  .B\\  =  17-2 
A«  =  .^A=  20.0 

A7  =  .tf*  =  24.9 
Ae  =  .rfft  =  29.2 
As  =  .  I'D8*  =  37.0 
A.  =  .#*  =  49-3 
As  ^  .i1o59  -  71.7 
A.  =  .  to  =122.0 
A  i  =  -o^o  =300.0 

In  like  manner/. 9  to/.,  can  be  found  for  any 
other  value  of/.  These  values  have  been  calcu- 
lated and  are  given  in  Table  No.  2,  up  to  p=60 
pounds,  advancing-  by  increments  of  one  pound. 

To  plot  the  adiabatic  line  by  means  of  Table 
No.  2:  Find  in  the  horizontal  line  with  p  the 
number  corresponding-  to  the  absolute  back 
pressure  on  your  card.  Then  in  the  same  verti- 
cal column  that  contains  your  absolute  back 
pressure,  and  opposite/. 9  find  the  value  of  /.9. 
Lay  this  off  on  line  .9  (Fig-.  5)  from  VVto  the 
same  scale  as  that  of  your  indicator  spring-.  Do 
the  same  for  /.8  /.7  to  /.,.  You  then  have  a 
series  of  points  throug-h  which  you  draw  the 
smooth  curve  c^  c  (Fig-.  5).  This  line  £,  c  is  the 
adiabatic  line. 

If  the  ammonia  gas  were  compressed  from 
point  c  (Fig-.  9)  up  to  the  condenser  pressure 
in  a  perfectly  tig-ht  and  non-conducting  cyl- 
inder without  loss  or  gain  of  heat,  then  the 
adiabatic  line  would  be  the  curve  traced  by  the 
indicator  pencil.  Now  if  there  is  no  leakag-e 
past  the  valves  or  piston,  this  adiabatic  line  will 


24  INDICATING    THK 

in  all  ammonia  compressors,  as  used  to-day, 
almost  overlie  the  compression  line  of  the  card 
for  its  whole  length  (see  Fig-.  9). 

The  water  jacket  does  not  seem  to  affect  the 
compression  line  to  any  great  extent.  The 
jacket  of  water  may  affect  the  relative  positions 
of  the  adiabatic  and  compression  curves,  during 
the  latter  one-fourth  or  one  fifth  of  the  stroke 
(when  the  gas  is  very  hot);  then  the  adiabatic 
line  will  be  seen  to  be  slightly  above  the  com- 
pression line  (see  Fig-.  9).  If  the  compression 
line  of  the  card  does  not  follow  very  nearly  the  adia- 
batic you  can  make  up  your  mind  that  something'  is 
wrong  in  connection  with  the  piston,  valves  or 
gaskets  of  the  compressor.  This  is,  of  course,  as- 
suming that  the  indicator  is  properly  connected; 
that  the  pipe  leading  from  the  cylinder  to  the  in- 
dicator is  short  and  of  small  bore,  say  >^-inch 
diameter,  and  that  this  pipe  is  well  insulated 
from  the  cooling  effect  of  water  in  the  jacket. 
One  thing  is  certain,  the  compression  curve  can 
never  lie  above  the  adiabatic  line  if  the  compressor 
is  working  properly.  I  will  take  up  and  discuss 
the  conclusions  that  can  be  drawn  from  the  dif- 
ferent relations  of  the  adiabatic  and  compression 
lines  as  soon  as  I  have  indicated  how  to  draw  the 
isothermal  line  on  the  indicator  card. 


AMMONIA   COMPRESSOR. 


CHAPTER  IV. 


THE  ISOTHERMAL  CURVE. 

If  there  is  no  leakage  to  or  from  the  cylinder 
during-  compression,  and  if  the  cylinder  walls, 
head  and  piston  are  perfect  conductors  of  heat, 
surrounded  by  a  suitable  cooling-  medium,  then 
the  temperature  of  the  g-as  will  remain  constant 
during-  its  compression,  and  we  will  have  the  iso- 
thermal line  traced  by  the  indicator  pencil.  No 
ammonia  compressor  is  running-  to-day  that  will 
give  a  compression  line  like  this  on  the  indicator 
card.  I  doubt  very  much  if  an  ammonia  com- 
pressor will  ever  be  built  that  will  give  a  card 
where  the  compression  line  will  approach  it  in 
any  great  degree.  There  is  such  a  great  amount 
of  heat  generated  during  compression  that  about 
all  that  can  be  hoped  for  is  to  prevent  too  great  an 
accumulation  of  heat  in  the  metals  of  the  cylinder. 
This  is  all  that  I  believe  is  accomplished  by  the 
water  jacket,  even  in  the  best  compressors  built. 

The  isothermal  line  is  more  easily  calculated 
than  the  adiabatic.  It  is  represented  by  the 
formula  ^^=^2^.  That  is,  the  initial  pressure 
times  the  initial  volume  is  equal  to  the  final 
pressure  times  the  final  volume.  Takings  as  1, 

then  pXl=-fi\xVi  orPi=^->  Now  take  values 
of  z>j  from  .9  to  .1  as  we  did  in  the  case  of  the 
adiabatic  line;  then  as  p  represents  the  back 
pressure  in  pounds  absolute,  the  different  values 
of  p^  as  f,9  p.%  p^  to^.t,  will  be  found  by 
dividing  the  absolute  back  pressure  p  by  the 

(3) 


26 


INDICATING    THE 


TABLE  NO.  3. 

ISOTHERMAL    CONSTANTS. 


p. 

15 

16 

17 

18 

19 

20 

£1 

££ 

£3 

«4 

P.  9 

16.7 

17.8 

18.9 

20.0 

21.1 

22.2 

23.3 

24.5 

25.6 

26.7 

P.  8 

18.7 

20.0 

21.2 

22.5 

23.7 

25.0 

26.2 

27.5 

28.7 

30.0 

P.7 

21.4 

22.8 

24.3 

25.7 

27.1 

28.6 

30.0 

31.4 

32.8 

34.3 

P.6 

25.0 

26.7 

27.3 

30.0 

31.7 

33.4 

35.0 

36.7 

38.4 

40.0 

P.B 

30.0 

32.0 

34.0 

36.0 

38.0 

40.0 

42.0 

44.0 

46.0 

48.0 

P.  4 

37.5 

40.0 

42.5 

45.0 

47.5 

50.0 

52.5 

55.0 

57.5 

60.0 

P.  3 

50.1 

53.4 

56.7 

60.1 

63.4 

66.7 

70.1 

73.4 

76.7 

80.1 

P    9 

75.0 

80.0 

85.0 

90.0 

95.0 

100.0 

105.0 

110.0 

115.0 

120.0 

XT  •  2 

P.I 

150.0 

160.0 

170.0 

180.0 

190.0|200.0 

210.0 

220.0 

230.0 

•240.0 

P* 

«5 

«6 

«7 

«8 

£9 

3O 

31 

338 

33 

34 

P-9 

27.8 

28.9 

30.0 

31.1 

32.2 

33.3 

34.4 

35.6 

36.7 

37.8 

P.  8 

31.2 

32.5 

33.7 

35.0 

36.2 

37.5 

38.7 

40.0 

41.2 

42.5 

P.  7 

35.7 

37.1 

38.6 

40.0 

41.4 

42.8 

44.3 

45.7 

47.2 

48.6 

P.  6 

41.7 

43.4 

45.0 

46.7 

48.3 

50.0 

51.7 

53.4 

55.0 

56.7 

P.  5 

50.0 

52.0 

54.0 

56.0 

58.0 

60.0 

62.0 

64.0 

66.0 

68.0 

P.  4 

62.5 

65.0 

67.5 

70.0 

72.5 

75.0 

77.5 

80.0 

82.5 

85.0 

P.  3 

83.4 

86.7 

90.1 

93.4 

96.7 

100.1 

103.4 

106.7 

110.1 

113.4 

P.  2 

125.0 

130.0 

135.0 

140.0 

145.0 

150.0 

155.0 

160.0 

165.0 

170.0 

P.1 

250.0 

260.0 

270.0 

280.0 

290.0 

300.0 

310.0 

320.0 

330.0 

340.0 

p 

35 

36 

87 

3$ 

39 

4O 

41 

42 

43       44 

P-9 

38.9 

40.0 

41.2 

42.3 

43.4 

44.5 

45.6 

46.7 

47.8 

48.9 

P'8 

43.7 

45.0 

46.2 

47.5 

48.7 

50.0 

51.2 

52.5 

53.7 

55.0 

P.  7 

50.0 

51.4 

52.8 

54.3 

55.7 

57.2 

58.6 

60.0 

61.4 

62.8 

P.  6 

58.4 

60.0 

61.7 

63.4 

65.0 

66.7 

68.4 

70.0 

71.7 

73.4 

P-  5 

70.0 

72.0 

74.0 

76.0 

78.0 

80.0 

82.0 

84.0 

86.0 

88.0 

P-4 

87.5 

90.0 

92.5 

95.0 

97.5 

100.0 

102.5 

105.0 

107.5 

110.0 

P.3 

116.7 

120.1 

123.4 

126.7 

130.1 

133.4 

136.7 

140.1 

143.4146.7 

P.  2 

175.0 

180.0 

185.0 

190.0 

195.0 

200.0 

205.0 

210.0 

215.0j220.0 

P.I 

350.0 

360.0 

370.0 

380.0 

390.0 

400.0 

410.0 

420.0 

430.0|440.0 

p. 

45 

46 

47 

48 

49 

50 

51 

52 

53 

54 

P-9 

50.0 

51.2 

52.3 

53.4 

54.5 

55.6 

56.7 

57.8 

58.9 

60.0 

P-8 

56.2 

57.5 

58.7 

60  0 

61.2 

62.5 

63.7 

65.0 

66.2 

67.5 

P-7 

64.3 

65.7 

67.2 

68.5 

70.0 

71.4 

72.8 

74.3 

75.7 

77.2 

P.  6 

75.0 

76.7 

78.4 

80.0 

81.7 

83.4 

85.0 

86.7 

88.4 

90.0 

P.  5 

90.0 

92.0 

94.0 

96.0 

98.0 

100.0 

102.0 

104.0 

106.0 

108.0 

P,  4 

112  5 

115.0 

117.5 

120.0 

122.5 

125.0 

127.5 

130.0 

132.5 

135.0 

P.3 

150.0153.4 

156.7 

160.0 

163.4 

166.7 

170.0 

173.4 

176.7 

180.0 

p]2 

225.0230.0 

235.0 

240.0 

245.0 

250.0 

255.0 

260.0 

265.0 

270.0 

P.'t 

450.0|460.0 

470.0 

480.0 

490.0 

500.0 

510.0 

520.0 

530.0|540.0 

p. 

55 

56 

57 

58 

59 

60 

P-9 

61.2 

62.3 

63.4 

64.5 

65.6 

66.7 

P-8 

68.7 

70.0 

71.2 

72.5 

73.7 

75.0 

P-7 

78.5 

80.0 

81.4 

82.8 

84.3 

85.7 

P-  6 

91.7 

93.4 

95.0 

96.7 

98.4 

100.0 

P.  5 

110.0 

112.0 

114.0 

116.0 

118.0 

120.0 

P-4 

137.5 

140.0 

142.5 

145.0 

147.5 

150.0 

P.3 

183.4 

186.7 

190.1 

193.4 

196.7 

200.1 

P.  2 

275.0 

280.0 

285.0 

290.0 

295.0 

300.0 

P.I 

550.0 

560.0 

570.0 

580.0 

590.0 

600.0 

AMMONIA    COMPRESSOR. 


27 


volume  z;.9,  z>.8  tox^.     Let^>— 15  pounds  abso- 
lute; then 

/.9=    |=  16.7 

P.B-  15»=  18.7 

A7=    f—  21.4 

Ae-    i-  25.0 

As=    1=  30.0 

/>.4=    \=  37.5 

/.a=    1=  50.1 

AS-    1=  75.0 

/.!=  if =150.0 

In  like  manner  ^.9  to^.t  can  be  found  for  any 
other  value  of  p.  These  values  have  been  cal- 
culated, and  are  given  in  Table  No.  3,  up  to  sixty 
pounds. 

To  plot  the  isothermal  line  by  means  of  Table 
No.  3,  proceed  the  same  as  explained  in  regard 
to  the  adiabatic  line.  Fig".  6  shows  a  card  upon 
which  this  has  been  done. 


28 


INDICATING    THE 


AMMONIA   COMPRESSOR.  29 


CHAPTER  V. 

DISCUSSION    OF    THE     ADIABATIC    AND     ISOTHERMAL 
CURVES. 

Now,  let  us  discuss  the  conclusions  that  may 
be  drawn  by  inspecting-  a  card  having-  these 
adiabatic  and  isothermal  lines  drawn  on  it. 
First,  let  us  discuss  the  adiabatic  line.  Take 
the  card  shown  by  Fig-.  7.  Here  is  seen  that  the 
compression  line  is  above  the  adiabatic  line. 
Something-  is  wrong-;  what  is  it?  Let  us  consider 
what  conditions  could  exist  that  would  cause  this 
condition  of  affairs.  It  is  evident  that  the  press- 
ure in  the  cylinder  increases  faster  than  could 
be  caused  by  the  action  of  the  piston.  The  same 
conditions  that  cause  the  compression  line  to  lie 
above  the  adiabatic  line  during-  compression 
will  cause  the  cylinder  to  be  cheated  out  of 
part  of  its  full  charg-e  of  g-as  from  the  suction 
pipe.  The  reason  is  that  the  hig-h  pressure 
gas  from  the  condenser  is  leaking-  into  the 
cylinder,  either  through  leaky  discharge  valves, 
their  gaskets  or  the  cylinder  head  gasket  be- 
tween the  cylinder  and  the  discharge  port. 
Therefore,  we  pump  much  less  gas  than  we 
should.  It  also  takes  more  power  to  run  the 
compressor,  as  will  be  evident  from  the  in- 
creased area  of  the  diagram.  It  will  not  take 
long  for  a  compressor  to  waste  enough  coal  to 
buy  a  first-class  indicator,  if  this  condition  of 
affairs  is  allowed  to  go  on  for  any  great  length 
of  time. 

In  large  machines  the  loss  will  be  very  great. 


30 


INDICATING   THE 


AMMONIA    COMPRESSOR.  31 

The  engineer  should  take  off  the  cylinder  head 
and  examine  the  cylinder  head  gasket.  If  it 
looks  bad,  replace  it  with  a  new  one.  Try  the 
valves  with  the  fingers,  and  see  that  no  scale  or 
foreign  matter  has  attached  itself  to  the  valve 
or  its  seat.  Also  examine  the  valve  cage  gas- 
kets. After  having  done  all  that  you  can  to 
remedy  the  trouble,  by  a  careful  examination, 
replace  the  cylinder  head,  and  connect  a  press- 
ure gauge  to  the  indicator  connection.  Allow 
the  condenser  pressure  to  act  upon  the  outer 
faces  of  the  discharge  valves.  If  the  pressure, 
as  shown  by  the  gauge,  remains  the  same  or  in- 
creases very  slowly  you  have  remedied  the 
difficulty.  Otherwise,  if  the  pressure  increase 
rapidly,  you  have  not. 

In  nine  cases  out  of  ten  the  engineer  will  find 
upon  his  first  careful  examination  of  the  gaskets 
and  valves  that  the  gasket  is  defective,  or  that 
there  is  some  foreign  substance  in  the  valve 
seat.  It  may  be  that  the  valves  need  regrinding. 
This  is  a  point  that  is  rather  difficult  to  deter- 
mine by  a  mere  inspection,  hence  the  pressure 
gauge  test. 

Now  let  us  examine  the  card  as  shown  by  Fig. 
8.  Here  the  compression  line  is  some  little  dis- 
tance below  the  adiabatic  line  ec.  It  approaches 
the  isothermal  line  dc.  Some  engineers  might 
thoughtlessly  say:  "What  a  fine  card!  how  effi- 
cient the  water  jacket  must  be!"  etc.  But,  as 
I  said  before,  compressors  "are  not  built  that 
way."  By  apparently  being  so  good  the  card 
gives  ample  evidence  of  a  very  bad  state  of  affairs 
within  the  compressor. 

Let  us  see  what  conditions   could  give  this 


32 


INDICATING    THK 


AMMONIA   COMPRESSOR.  33 

result.  It  is  evident  that  the  pressure  is  not  as 
great  at  any  point  on  the  curve  as  it  should  be. 
What  is  the  cause  of  this?  Some  of  the  gas  has 
leaked  out  of  the  cylinder,  either  by  leaky  suc- 
tion valves  or  their  gaskets.  The  cylinder  head 
gasket  may  be  defective  between  the  suction 
port  and  the  cylinder,  or  you  may  have  a  leaky 
piston.  It  is  evident  that  a  sort  of  rubber  ball 
action  is  going  on  in  the  cylinder.  Part  of  the 
gas  is  compressed  and  expanded  between  the 
suction  pipe  and  the  cylinder,  in  place  of  being 
discharged  into  the  condenser.  The  gas  is  in 
part  pumped  over  and  over  again,  thereby  cut- 
ting down  the  capacity  of  the  machine.  Remove 
the  cylinder  head,  examine  the  gaskets  and 
valves.  Do  all  that  you  can  by  a  careful  inspec- 
tion to  make  good  the  trouble.  Then  replace 
the  cylinder  head  and  connect  a  pressure  gauge 
to  the  indicator  connection.  Compress  the  gas  in 
the  cylinder  so  as  to  have  a  high  pressure.  Note 
the  pressureon  the  gauge.  If  it  does  not  decrease, 
or  if  it  decreases  very  slowly,  you  have  remedied 
the  trouble.  If  it  decreases  rapidly,  either  the 
valves  need  regrinding,  the  piston  needs  new 
rings  or  the  cylinder  should  be  rebored,  or  all 
these  troubles  may  exist  at  once.  After  having 
had  the  valves  reground  if  the  pressure  test,  as 
indicated  above,  still  shows  a  rapidly  decreasing 
pressure,  you  would  better  call  in  the  agent  for 
your  machine,  and  let  him  decide  whether  the 
piston  rings  or  the  boring  of  the  cylinder  are 
at  fault. 

Fig.  9  shows  the  relations  of  the  compression 
curve  and  adiabatic  line,  e  c,  that  your  compressor 
should  give  if  in  perfect  condition.  It  has  prob- 


34 


INDICATING    THK 


AMMONIA    COMPRESSOR.  35 

ably  occurred  to  you  while  reading-  the  above  that 
you  might  do  all  of  your  testing-  with  a  pressure 
gauge,  in  place  of  bothering-  with  an  indicator. 
This  is  true,  in  a  way.  Engineers  who  do  not 
own  an  indicator  may  make  all  the  above  tests 
in  regard  to  leaky  valves,  etc.,  by  connecting  a 
pressure  gauge  to  the  indicator  cock  and  pro- 
ceeding as  explained  above. 

The  indicator  card  is  a  valuable  permanent 
record  of  what  your  compressor  is  doing.  It 
should  be  taken  every  week,  dated  and  filed  away 
for  future  reference.  A  steel  indicator  is  pre- 
ferred for  ammonia  work.  However,  you  may 
use  your  composition  indicator  without  fear  of 
damage  if  you  keep  it  well  oiled,  and  thoroughly 
clean  it  as  soon  as  you  have  finished  your  test. 


36 


INDICATING    THE 


AMMONIA   COMPRESSOR.  37 


CHAPTER  VI. 

FINDING  THE  HORSE  POWER  OF  AN  INDICATOR  CARD. 

To  obtain  the  horse  power,  or  work  of  com- 
pression, represented  by  the  indicator  card  it  is 
convenient  to  have  a  planimeter,  and  thus  meas- 
ure the  area  of  the  card.  Then  divide  the  area 
thus  found  by  the  length  of  the  card  in  inches, 
and  multiply  the  result  by  the  scale  of  the  spring- 
used.  The  result  is  the  mean  effective  pressure, 
expressed  as  M.  E.  P.  The  mean  effective  press- 
ure is  the  average  pressure  of  the  gas  in  the 
cylinder  from  the  beginning  of  suction  to  the  end 
of  discharge. 

I  will  not  go  into  the  method  of  using  the 
planimeter,  as  it  is  fully  explained  in  the  instruc- 
tions that  are  furnished  with  each  instrument, 
and  also  in  Parts  II  and  III  of  this  book.  If  you 
are  not  fortunate  enough  to  own  a  planimeter,  and 
cannot  borrow  one,  you  can  obtain  the  M.  E.  P.  as 
follows :  In  Fig.  10  you  should  already  have 
your  card  divided  into  ten  equal  spaces,  vl  z'.9, 
z>.8  z/.7,  etc.  All  that  is  necessary  is  to  find  the 
average  heights  of  these  areas  that  are  included 
between  the  vertical  lines  as  ^.9^.8  and  the  ad- 
mission and  compression  or  discharge  lines. 
Divide  each  of  these  spaces,  v^v,9  toz'.jZ',,,  into 
two  equal  parts,  and  draw  through  these  divis- 
ions the  dotted  lines  as  shown,  which  are  num- 
bered 1,  2  to  10. 

Measure  the  length  of  each  line  from  the 
admission  line  to  where  it  cuts  the  compression 
or  discharge  curve,  using  the  same  scale  as  that 


38  INDICATING    THE 

of  the  indicator  spring-  used.  Add  tog-ether  these 
leng-ths  and  divide  the  result  by  10.     The  quo- 
tient is  then  the  average  height  or  the  M.E.P. 
Having  the  M. E.P.,  the  horse  power  is  readily 

found  by  the  following  simple  formula: 

_  nXlXaX  (M.E.P.) 
'      '  7  33,000 

Where  72— strokes  (not  revolutions)  per  minute. 
/=length  of  stroke  in  feet. 
tf=area  of  piston  in  square  inches. 
M.  E.P.=mean  effective  pressure. 

Every  engineer  should  know  the  constant  for 
his  compressor. 

It  is  evident  that  in  the  above  formula 


33,000 

is  constant  for  all  conditions  or  tests.  This  value, 
33  ooo  *  *s  ^e  cons^an^  for  your  compressor,  and  is 
indicated  by  C.  Therefore  the  horse  power  is 

H.  P.=  CX  n  X  (M.  E.  P.) 

The  horse  power  of  the  steam  engine  is 
obtained  in  the  same  way.  Only  remember  that 
whereas  your  compressor  may  have  been  single- 
acting,  as  is  assumed  for  the  above  formula,  your 
engine  is  double-acting;  therefore  you  should 
multiply  your  strokes  by  2,  and  your  engine  con_ 
stant  is  approximately  33  ^  This  is  also  the 
constant  for  a  double-acting  compressor.  In  a 
double-acting  compressor  or  a  steam  engine  the 
area  of  one  side  of  the  piston  must  have  de- 
ducted from  it  the  area  of  the  piston  rod,  thus 
giving  the  effective  area  of  the  piston.  The  true 
constant  for  that  side  of  the  piston  will  then  be 
~~33  000  *  ai  bein§"  the  area  of  the  piston  rod  in 
square  inches,  The  difference  between  the  H.  P. 
of  the  steam  engine  and  that  of  the  compressor 
is  the  friction  of  the  machine. 


AMMONIA    COMPRESSOR.  39 


CHAPTER  VII. 

ACTUAL    DISPLACEMENT    OF    A    COMPRESSOR. 

The  actual  displacement  of  the  compressor 
should  be  known.  We  know  that  the  compressor 
does  not  pump  the  weight  of  gas  that  it  should, 
as  figured  from  its  theoretical  displacement, 
the  reason  being,  as  stated  by  Prof.  Deiiton, 
that  the  gas  is  rarefied  during  suction  by  coming 
in  contact  with  the  hot  walls  of  the  cylinder. 

It  is  evident  that  if  the  gas  is  rarefied  the 
weight  of  a  given  volume  of  gas  would  be  less 
after  rarefaction  than  before.  Consequently 
our  compressor  may  vary  in  its  actual  capacity 
from  70  per  cent  to  90  per  cent  of  the  theoretical 
capacity,  these  two  figures,  70  per  cent  and  90 
per  cent,  being  extreme  cases  that  are  rarely  if 
ever  reached.  The  common  value  of  the  actual 
capacity  is  from  75  per  cent  to  80  per  cent  of  the 
theoretical  capacity. 

My  theory  in  regard  to  this  rarefaction  is 
that  as  the  gas  enters  the  cylinder  through  the 
narrow  annular  openings  between  the  hot  valves 
and  their  seats,  it  is  superheated  and  thus  rare- 
fied. There  is  only  a  brief  interval  between  the 
end  of  compression  and  the  beginning  of  suction. 
When  suction  begins  the  cylinder  head  and  valves 
are  at  their  maximum  temperature.  Consequently 
I  could  think  of  no  better  way  of  heating  a  gas 
than  that  of  forcing  it  through  these  narrow  an- 
nular openings,  having  hot  metal  surfaces  to  pass 
by.  The  head  and  valves  should  be  cooled  by 
some  means  other  than  the  gas  to  be  pumped. 


40  INDICATING    THK 

The  gas  should  arrive  at  the  cylinder  as 
near  the  temperature  of  the  boiling-  point  of  the 
liquid  ammonia,  due  to  its  back  pressure,  as 
possible.  Every  degree  of  superheating-  cuts 
down  the  actual  capacity  of  the  compressor.  It 
is  well  known  that  a  gas  will  expand  T  J-T  of  its 
volume  at  0°  F.  for  every  degree  of  increase  of 
its  temperature.  The  suction  pipe  to  a  com- 
pressor should  be  thoroughly  insulated.  The 
vapor  from  the  expansion  coils  should  not  be 
used  for  any  cooling  purpose  whatsoever.  Cool- 
ing the  liquid  ammonia  by  means  of  the  return 
vapor  is  poor  practice.  To  be  sure,  it  is  an 
advantage  to  have  the  ammonia  arrive  at  the  ex- 
pansion valve  as  cold  as  possible,  but  it  is  more 
disadvantageous  to  warm  up  the  vapor  than  not 
to  cool  down  the  liquid  with  it. 

It  will  be  evident  how  poor  the  gas  is  in  cool- 
ing power  when  it  is  remembered  that  one  pound 
of  vapor  only  has  a  cooling  effect  of  .5  British 
thermal  units  for  every  degree  F.  that  it  warms 
up;  while  a  pound  of  the  liquid  ammonia  has  while 
vaporizing  a  cooling  effect  of  555  B.  T.  U.,  on  an 
average,  or  over  one  thousand  times  as  much. 
(Cool  the  liquid  ammonia  by  any  other  available 
means,  but  not  by  the  return  ammonia  vapor.) 

If  the  expansion  coils  or  receptacle  are  prac- 
tically built,  if  the  coils  are  not  too  long,  you  will 
have  no  trouble  with  liquid  ammonia  coming 
over  to  your  machine.  Should  you  be  unfortunate 
enough  to  have  a  brine  tank  or  expansion  coils 
that  will  squirt  the  liquid  in  the  form  of  a  spray 
over  to  the  compressor,  you  would  better  put  a 
separator  in  your  suction  pipe  or  else  get  a  more 
efficient  brine  tank  or  expansion  coils. 


fi  UNIVERSITY  J 

AMMONIA    COMPRESSOR?**"11""'       1^*^41 

The  talk  about  where  the  frost  line  should  or 
should  not  stop  on  the  suction  pipe  is  all  bosh. 
The  frost  should  go  right  up  to  and  around  the 
compressor  cylinder  if  it  is  uninsulated.  But 
better  still,  the  suction  pipe  and  the  cylinder 
should  be  thoroughly  insulated  from  the  effect 
of  heat  from  outside  sources.  It  is  necessary 
to  know  the  temperature  of  the  boiling  point  of 
the  ammonia  in  your  expansion  coils,  and  also 
the  temperature  of  the  gas  at  the  suction 
entrance  to  your  compressor.  So  long  as  the  tem- 
perature of  the  gas  at  the  compressor  is  5°  or 
10°  F.  above  that  of  the  boiling  ammonia, 
there  will  be  no  danger  of  getting  liquid  over 
to  your  machine. 

I  would  not  let  the  gas  get  colder  than  10° 
above  that  of  the  boiling  point  of  the  ammonia. 
Probably  there  are  hundreds  of  plants  that  can- 
not follow  this  advice  because  they  have  squirt- 
ing expansion  coils.  But  the  time  is  not  far 
distant  when  these  plants  will  throw  aside  their 
squirting  coils  and  substitute  expansion  devices 
which  do  not  tend  to  squirt  the  liquid  ammonia 
like  an  atomizer.  The  liquid  ammonia  should 
be  allowed  to  boil  in  such  a  vessel  that  there  is 
ample  room  for  the  vapor  to  escape  without 
dragging  along  some  of  the  liquid  with  it.  I 
have  tried  both  kinds,  squirting  coils  and  proper 
expansion  vessels,  and  I  would  not  take  an  or- 
dinary coil  brine  tank  for  a  gift  unless  I  could 
use  it  for  some  other  purpose  than  for  a  brine 
tank. 

Now  to  determine  the  actual  displacement  of 
your  compressor.  If  you  use  the  brine  system 
this  can  readily  be  done.  Get  the  specific  gravity 

(4) 


42  INDICATING    THK 

of  your  brine  by  means  of  a  hydrometer.  If  you 
do  not  own  a  hydrometer,  weigh  equal  volumes 
of  your  brine  and  water.  Divide  the  weight  of 
the  brine  by  that  of  the  water.  The  result  is  the 
specific  gravity  of  your  brine.  Now  look  up  in 
the  tables  (see  Part  IV)  the  corresponding 
specific  heat.  Take  several  readings  of  the  tem- 
perature of  your  brine  to  tank  and  also  of  brine 
from  tank.  Average  the  readings  of  the  inlet 
brine  and  also  average  those  of  the  outlet  brine. 
Subtract  the  results.  This  is  of  course  the 
number  of  degrees  that  you  have  cooled  your 
brine  through. 

Find  the  weight  of  brine  circulated  per  min- 
ute by  your  pump.  To  do  this,  multiply  the 
strokes  of  your  pump  per  minute  by  the  length 
of  stroke  in  inches  by  the  piston  area  in  square 
inches,  and  divide  the  result  by  1,728;  this  gives 
the  cubic  feet  pumped  per  minute ;  multiply  this 
by  the  weight  of  a  cubic  foot  of  your  brine,  to 
obtain  the  weight  pumped  per  minute.  If  your 
pump  is  in  good  condition  you  should  multiply 
this  result  by  .95,  .95  being  the  probable  actual 
capacity  of  your  brine  pump. 

Having  now  the  weight  in  pounds  of  the  brine 
pumped  per  minute,  multiply  this  weight  by  the 
degrees  F.  change  in  temperature  of  your  brine 
in  the  brine  tank,  and  multiply  this  result  by 
the  specific  heat  of  your  brine.  Now,  divide 
the  above  result  by  200,  and  your  final  answer 
is  the  tons  of  refrigeration  that  you  are  doing 
per  twenty-four  hours. 

One  ton  refrigeration  in  twenty-four  hours 
=  2,000  X  142  B.  T.  U. ;  142  B.  T.  U.  is  the  latent 
heat  of  liquefaction  of  ice.  2,000  X  142  =  284,000 


AMMONIA    COMPRESSOR.  43 

B.  T.  U.  per  twenty-four  hours  =  ^^  =  200, 

nearly,  B.  T.  U.  per  minute.  Twenty-four  hours 
=  1,440  minutes.  Expressed  in  the  form  of  a 
formula,  the  above  will  read: 


200 

7?—  tons  refrigeration  per  twenty-four  hours. 

/  =  temperature  warm  brine;  t^  =  temper- 
ature cold  brine. 

5  =  specific  heat  of  brine. 

TV  =  weight  of  brine  circulated  per  minute. 

Now,  turn  to  your  ammonia  tables  (see  Part 
IV)  and  find  the  weig-ht  of  a  cubic  foot  of  vapor 
of  ammonia  at  the  back  pressure  at  which  you 
are  running-.  Also  look  up  the  latent  heat  of 
vaporization  at  this  pressure,  and  the  boiling- 
point  of  the  liquid  ammonia.  Take  the  tempera- 
ture of  your  liquid  ammonia  just  before  it  enters 
the  expansion  valve.  If  your  liquid  pipe  is  insu- 
lated, as  it  should  be,  this  temperature  will  be 
about  the  same  as  that  of  the  water  coming- 
from  your  condenser. 

Subtract  the  boiling-  point  of  the  ammonia 
from  this  temperature.  As  the  specific  heat  of 
liquid  ammonia  is  1,  this  gives  the  number  of 
B.  T.U.  that  the  liquid  must  be  cooled  to  bring- 
it  to  the  boiling-  point.  As  this  has  to  come  from 
the  heat  of  vaporization,  we  subtract  it  from 
the  heat  of  vaporization,  leaving-  as  a  result  the 
available  cooling-  effect  in  B.  T.  U.  of  one  pound 
of  liquid  ammonia  under  our  conditions.  Ex- 
pressed in  the  form  of  a  formula,  the  above  be- 
comes — 

R  X  200  200  X 

~~  ~  ~ 


44  INDICATING    THK 

r  =  heat  of  vaporization. 

/2  =  temperature  of  ammonia  at  expansion 
valve. 

/3  =  temperature  of  ammonia  at  boiling-  point. 

W=  pounds  of  ammonia  circulated  per  minute. 

Take  the  theoretical  displacement  in  cubic 
feet  of  your  compressor  per  minute  =  D;  mul- 
tiply this  by  the  weight  of  a  cubic  foot  of  vapor 
of  ammonia  at  the  back  pressure  you  are  using 
(see  Part  IV  for  tables).  The  result  is  the  theo- 
retical number  of  pounds  of  ammonia  pumped 
by  your  compressor  =  Wl .  Then  Dl  —the  actual 

capacity  of  your  compressor;  J9,  =jy 

EXAMPLES. 

JVo.  i. — Required  the  horse  power  of  card  (see 
Fig.  id). 

The  compressor  has  two  single-acting  cylin- 
ders, each  twelve  inches  in  diameter,  stroke— 
eighteen  inches;  forty  revolutions  per  minute; 
scale  of  spring,  40. 

Solution. — Measure  height  of  lines  1,  2,  3  to 
10,  with  a  40  scale.  They  measure  88,  88,  88,  58, 
35,  22,  13,  7,  4,  1.  The  sum  of  these  figures  is 
404.  Dividing  by  10,  the  result  is  40.4  = 
M.  E.  P. 

The  constant  for  this  compressor  is 

/Xfl        1.5  X  113  = 
33,000  33,000 

H.  P.  =CX  »XM.  E.  P. 
.  • .  H.  P.  =  .00514  X  40  X  40.4  =  8.3. 

As  there  are  two  cylinders,  we  must  obtain 
also  the  horse  power  of  the  other  card ;  if  it  is 
the  same  as  this  card,  then  the  horse  power  of 
both  cylinders  is  8.3  X  2=  16.6. 


AMMONIA    COMPRKSSOR.  45 

If  the  horse  power  of  the  steam  engine  is  20, 
then  20  —  16.6  =  3.4  =  friction  of  machine  =  $••#  , 
17  per  cent  of  that  of  the  steam  cylinders. 

This  is  very  good.  The  friction  will  usually 
be  about  20  per  cent. 

No.  2.  —  Required  the  refrigeration  per  day. 

Brine  pumped  per  minute  =  667  pounds. 

Change  in  temperature  of  brine  =3°  F.— 
t-t\. 

Specific  heat  of  brine  =  .8. 


No.  3.  —  Required  the  actual  capacity  of  the  com- 
pressor, the  theoretical  capacity  being  100  per  cent. 

Temperature  of  liquid  ammonia  to  expansion 
valve  =  70°  F.;  r  =  572,  *3  =  —  28  for  an  absolute 
back  pressure  of  fifteen  pounds. 

y?=8,  r  =  572,  ^  =70°F.,  *8=  —  28G  F. 

J~)  vx  O  C\(\ 

•  '.    W==-  -  r  I  /8  =3.018  pounds  per  minute. 
r  —  »2~r^ 

The  theoretical  displacement  of  the  compres- 
sors is  113X182X40=94  cubic  f  eet  er  minute 


The  weight  of  a  cubic  foot  of  vapor  of  ammonia 
at  15  pounds  absolute  is  .056  pounds  .*.  94X.056= 
5.26  pounds^  W^  the  theoretical  capacity  of  the 

W        ^        3.018      _,_ 
compressor  .*.  jrr  =  D^  =--~-j£  =57.4  per  cent  = 

rr    -^  O«  ^D 

the  actual  capacity  of  the  compressor.  This  is 
too  small,  consequently  you  should  find  out  by 
your  adiabatic  line  where  the  trouble  is. 


46  INDICATING    THK 


CHAPTER  VIII. 

SPECIAL    FAULTS   AS   SHOWN    BY    CARDS. 

Fig-.  11  shows  a  card  when  the  suction  valve 
has  too  strong-  a  spring-  or  a  valve  that  is  inclined 
to  stick  to  its  seat.  (See  distorted  heel  at  a. } 

Fig-.  12  shows  a  card  where  the  line  a  a  is 
drawn  to  scale  at  a  vertical  distance  above  the 
atmospheric  line  A  A,  equal  to  the  suction  press- 
ure in  the  suction  pipe.  This  shows  that  the 
suction  valve  spring-  is  too  strong-. 

Fig".  13  shows  a  card  where  the  line  bb  has 
been  drawn  by  connecting-  the  indicator  to  the 
suction  pipe  and  line  a  a  by  connecting-  the  indi- 
cator to  the  discharg-e  pipe.  These  lines  should 
be  about  as  shown  on  the  card.  The  lines  a  a 
and  bb  can  best  be  laid  off  to  scale  above  A  A, 
corresponding-  to  the  pressures  in  these  pipes, 
as  shown  by  the  pressure  g-auge,  althoug-h  they 
may  be  drawn  by  the  indicator  pencil  if  the  suc- 
tion and  discharg-e  pipes  are  tapped  and  con- 
nected to  the  indicator. 

Fig-.  14  shows  a  card  with  a  line,  a  a,  drawn  to 
scale  at  a  distance  above  line  A  A  equal  to  the 
pressure  in  the  discharg-e  pipe.  This  indicates 
too  stiff  discharg-e  valve  spring's. 


AMMONIA    COMPRKSSOK. 


47 


48 


INDICATING    THK 


AMMONIA    COMPRESSOR. 


49 


50 


INDICATING    THK 


AMMONIA    COMPRESSOR.  51 


CHAPTER  IX. 

WET  COMPRESSION  SYSTEM  INDICATING. 

Fig's.  15  and  16  are  reproduced  from  cards 
furnished  me  by  the  Fred  W.  Wolf  Co.,  from  an 
18X30  inch  Linde  (wet  compression  system) 
compressor,  that  were  taken  at  the  Western 
Cold  Storage  Co.  plant,  on  November  9,  1898,  on 
which  I  have  drawn  the  adiabatic  line  c  d*  iso- 
thermal line  a  d  and  the  curve  of  saturation 
/;  d.  The  scale  of  spring-  for  these  cards  is  60. 
These  diagrams  were  given  me  as  representative 
cards,  and  seem  to  show  that  my  reasoning-,  as 
applied  to  the  dry  compression  or  water  jacket 
machines,  also  applies  to  the  wet  compression 
machines,  particularly  in  Fig-.  16. 

The  wet  compression  machines  differ  from 
the  dry  compression  machines  in  that  the  former 
injects  liquid  ammonia  into  the  cylinder  before 
compression  to  take  up  the  heat  of  compression, 
while  the  latter  surrounds  the  cylinder  with  a 
water  jacket  for  the  same  purpose. 

THE  CURVE  OF  SATURATION. 

If  the  ammonia  in  the  cylinder  at  the  begin- 
ning- of  compression  is  a  saturated  vapor,  and  if 
this  condition  (the  state  of  saturation)  is  main- 
tained throughout  compression,  then  there  will 
be  a  different  curve  from  the  adiabatic  and  iso- 
thermal traced  by  the  indicator  pencil.  This  is 
called  the  curve  of  saturation.  Any  point  on  this 
curve  has  its  ordinate  or  vertical  distance  from 
V  V  equal  to  the  pressure  in  the  cylinder,  and 
its  abscissa  or  horizontal  distance  f rom  d  Fequal 


52 


INDICATING    THK 


AMMONIA    COMPRESSOR  53 

to  the  relative  volume  in  cylinder,  the  initial  or 
(cylinder  full)  volume  being-  1.  The  ordinate 
being-  obtained  by  looking-  up  in  a  table  of  the 
properties  of  saturated  vapor  of  ammonia  the 
pressure  corresponding-  to  the  weig-ht  of  a  cubic 
foot  of  vapor  at  this  point,  this  weig-ht  being-  the 
product  of  the  relative  volume  at  this  point  and 
the  weig-ht  of  a  cubic  foot  of  vapor  at  the  absolute 
back  pressure  of  the  card.  Curves  b  d^  Figs.  15 
and  16,  are  curves  of  saturation.  This  curve 
can  be  readily  determined,  approximately,  from 
the  tables  of  the  properties  of  saturated  vapor  of 
ammonia  in  the  following-  manner: 

Find  from  the  tables  the  volume  in  cubic  feet 
per  pound  of  the  vapor  at  the  absolute  back 
pressure  of  the  card.  Multiply  this  value  by  .9, 
.8,  .7,  .6,  .5,  .4,  .3,  .2,  .1,  and  note  from  the  tables 
the  absolute  pressures  corresponding-  to  these 
new  volumes.  These  pressures  are  points  on 
the  curve  of  saturation  for  values,  .9,  .8,  .7,  .6,  .5, 
.4,  .3,  .2,  .1  of  v. 

For  example,  let  the  absolute  back  pressure 
be  twenty-one  pounds  per  square  inch.  We  find 
from  the  tables  that  the  number  of  cubic  feet  of 
vapor  per  pound  at  this  pressure  is  approxi- 
mately 12.834.  Then  it  follows  that— 

12.834 X. 9=11. 55  cu.  ft.  per  Ib.  •=  23.5  Ibs.  per  sq.  inch 

12.834  X.  8=10.27  "  =  26.5 

12.834X.7=  8.98  "  =310 

12.834X.6=  7.70  "  =  35.8 

12.834X.5=  6.42  "  =  43.0 

12.834X.4=  5.13  "  =  54.6 

12.834X.3=  3.85  "  =  59.7 

12.834X.2=  2.57  "  =113.7 

12.834X.1=  1.28  =232.0 

Laying-  off  these  values  of  pressures  found  on 
the  vertical  lines  to  scale  at  volumes  z;.fl,  z>.8,  v,^ 


54 


INDICATING    THK 


AMMONIA    COMPRESSOR.  55 

r.»;>  z'.5>  r4>  v.$i  ^.2*  ^  i»  from  the  vacuum  line,  we 
have  the  desired  points  on  the  curve  of  satura- 
tion. 

LIMITS  OF    COMPRESSOR. 

From  the  above  it  follows  that  the  adiabatic 
curve  will  be  traced  when  no  heat  is  taken  from 
or  given  to  the  gas  during-  compression.  The 
isothermal  curve  will  be  drawn  if  the  gas  is 
maintained  at  the  same  temperature  that  it  has 
at  the  beginning- of  compression.  Theoretically, 
the  g-as  should  be  quite  cold  at  the  beginning-  of 
compression,  say  from  10°  below  0^  F.  to  10° 
above  0°  F.  It  will  be  seen  that  compressors 
using  water  jackets  could  never  maintain  this 
line  unless  they  had  jacket  water  as  cold  or  colder 
than  these  temperatures  of  gas  at  the  beginning  of 
compression.  As  the  jacket  water  usually  rang-es 
anywhere  from  50°  F.  to  100°  F.,  it  is  clear  that 
no  heat  can  be  taken  from  the  compressed  g-as 
until  it  has  reached  this  temperature. 

This  will  explain  why  the  actual  curve  of  com- 
pression follows  the  adiabatic  curve  part  of  the 
way,  and  then  tends  toward  the  isothermal 
curve.  Where  the  actual  compression  curve 
leaves  the  adiabatic,  is  the  point  of  the  stroke 
where  the  jacket  water  is  just  beginning  to  "get 
in  its  work."  Therefore,  if  any  one  shows  you 
a  card  from  a  water  jacketed  dry  compressor 
that  approaches  the  isothermal  line  for  the  first 
half  of  the  stroke,  you  would  better  make  up 
your  mind  that  the  card  is  wrong. 

It  will  be  seen  in  Figs.  15  and  16  that  the  curve 
of  saturation  b  d  follows  very  closely  the  isother- 
mal curve.  In  wet  compression  machines  this 
curve  (the  curve  of  saturation )  is  aimed  at  bv 


56  INDICATING     THE 

injecting  enough  liquid  ammonia  into  the  cylin- 
der to  take  up  the  heat  of  compression.  If  this 
works  as  well  practically  as  it  does  by  theory, 
then  the  curve  of  saturation  is  possible,  and 
therefore  quite  a  reduced  area  of  card  is  obtained, 
indicating  less  power  required  to  compress  the 
ammonia. 

As  it  is  not  my  desire  to  compare  the  relative 
merits  of  the  wet  and  dry  compressors,  I  will 
only  add  that  to  be  fair  when  comparing  one  with 
the  other  the  question  should  be  thoroughly  in- 
vestigated as  to  whether  there  are  factors  that 
enter  into  the  value  of  each  machine  other  than 
those  shown  by  the  indicator  cards,  and  also 
to  note  that  cards  15  and  16,  which  are  taken  as 
representative  cards  of  the  wet  compression 
system,  are  almost  identical  with  what  is  ob- 
tained from  dry  compression  machines,  particu- 
larly Fig.  16. 


AMMONIA   COMPRESSOR.  57 


CHAPTER   X. 

INSTRUCTIONS  FOR   CONNECTING  INDICATOR  TO 
MACHINE. 

In  regard  to  connecting-  the  indicator  to  the 
compressor  and  arranging*  for  the  drum  motion, 
I  refer  the  reader  to  Chapters  II  and  III  of  Part 
II;  how  to  take  the  diagrams,  to  Chapter  IV, 
Part  II.  I  advise  the  use  of  a  reducing-  wheel, 
as  explained  in  Chapters  VII  and  VIII,  Part  III. 

The  reducing-  wheel  will  be  found  very  accu- 
rate and  simple,  and  can  be  used  with  any  of  the 
indicators  described.  Most  of  the  indicator 
manufacturers  have  these  reducing-  wheels  in 
stock,  specially  adapted  to  their  particular  make 
of  indicator. 

In  making-  the  ammonia  connection  with  the 
compressor  cylinder,  I  advise  the  use  of  a 
^2-inch  pipe  connection,  made  from  a  solid  piece 
of  iron  or  steel,  having-  a  hole  Y%  inch  diameter 
drilled  throug-h  it.  The  reason  for  using-  so 
small  a  bore  is  to  reduce  the  clearance  as  much 
as  possible.  This  connection  can  be  capped 
when  not  in  use,  or,  better  still,  fitted  with  a 
>^-inch  cock,  in  which  the  hole  in  the  plug-  has 
been  bushed  down  to  Y%  inch  diameter.  I  advise 
the  use  of  Coffin's  averaging-  instrument  for 
obtaining-  the  mean  effective  pressure  of  cards. 
This  instrument  gives  you  the  mean  effective 
pressure  direct  without  the  intermediate  steps 
of  calculation  necessary  with  the  common  plani- 
meter,  and  also  a  neat  board  upon  which  to 
measure  the  card. 

(5) 


INDICATING 

THE 

REFRIGERATING    MACHINE 


PART  II. 

INDICATING  THE  STEAM  ENGINE.* 


CHAPTER  I. 

THE   STEAM    ENGINE   INDICATOR. 

The  steam  engine  indicator,  invented  by 
James  Watt,  and  long-  kept  secret,  was  for  many 
years  after  its  secret  became  known,  strangely 
neglected  by  most  makers  and  users  of  steam 
engines. 

The  earlier  forms  of  the  instrument,  which 
preceded  that  invented  by  Richards,  were  so 
imperfect  and  so  ill  adapted  to  engines  running 
at  other  than  very  low  speeds,  that  their  indi- 
cations were  often  misleading,  more  often  unin- 
telligible, and  seldom  of  much  value  beyond 
revealing  the  point  of  stroke  at  which  the  valves 
opened  and  closed — a  most  valuable  service, 
alone  worth  the  cost  of  an  indicator,  but  only  a 
small  part  of  the  service  to  be  obtained  from  a 
really  good  instrument. 

The  general  principles,  on  which  the  best 
type  of  steam  engine  indicator  is  designed,  may 
be  briefly  stated  as  follows: 

A  piston  of  carefully  determined  area  is 
nicely  fitted  into  a  cylinder  so  that  it  will  move 

*Reprinted  by  courtesy  of  Crosby  Steam  Gage  and  Valve  Co.  from 
their  book  on  indicator  practice. 

59 


60  INDICATING    THE 

up  and  down  without  sensible  friction.  The 
cylinder  is  open  at  the  bottom  and  fitted  so  that 
it  may  be  attached  to  the  cylinder  of  a  steam 
engine  and  have  free  communication  with  its 
interior,  by  which  arrangement  the  under  side 
of  the  piston  is  subjected  to  all  the  varying 
pressures  of  the  steam  acting-  therein.  The 
upward  movement  of  the  piston — due  to  the 
pressure  of  the  steam — is  resisted  by  a  spiral 
spring  within  the  cylinder,  of  known  elastic 
force.  A  piston  rod  projects  upward  through 
the  cylinder  cap  and  moves  a  lever  having  at  its 
free  end  a  pencil  point,  whose  vertical  move- 
ment bears  a  constant  ratio  to  that  of  the  piston. 
A  drum  of  cylindrical  form  and  covered  with 
paper  is  attached  to  the  cylinder  in  such  a  man- 
ner that  the  pencil  point  may  be  brought  in 
contact  with  its  surface,  and  thus  record  any 
movement  of  either  paper  or  pencil.  The  drum 
is  given  a  horizontal  motion  coincident  with  and 
bearing  a  constant  ratio  to  the  movement  of  the 
piston  of  the  engine.  It  is  moved  in  one  direc- 
tion by  means  of  a  cord  attached  to  the  cross- 
head,  and  in  the  opposite  direction  by  a  spring 
within  itself. 

When  this  mechanism  is  properly  adjusted 
and  free  communication  is  opened  with  the  cyl- 
inder of  a  steam  engine  in  motion,  it  is  evident 
that  the  pencil  will  be  moved  vertically  by  the 
varying  pressure  of  steam  under  the  piston;  and 
as  the  drum  is  rotated  by  the  reciprocating  mo- 
tion of  the  engine,  if  the  pencil  is  held  in  contact 
with  the  moving  paper  during  one  revolution  of 
the  engine  a  figure  or  diagram  will  be  traced 
representing  the  pressure  of  steam  in  the 


STEAM    KNGINE.  61 

cylinder,  the  upper  line  showing-  the  pressure 
urging-  the  piston  forward,  and  the  lower  the 
pressure  retarding-  its  movement  on  the  return 
stroke. 

To  enable  the  engineer  to  more  correctly 
interpret  the  nature  of  the  pressures,  the  line 
showing-  the  atmospheric  pressure  is  drawn, 
which  indicates  whether  the  pressure  at  any 
part  is  greater  or  less  than  that  of  the  atmos- 
phere. 

From  such  a  diagram  may  be  deduced  many 
particulars  which  are  of  supreme  importance  to 
engine  builders,  engineers  and  the  owners  of 
steam  plants. 

WHAT   IS   THE   GOOD    OF    AN   INDICATOR? 

This  question  was  asked  by  a  young-  engi- 
neer who  had  come  to  examine  and  purchase  an 
indicator,  with  a  view  to  rendering  his  services 
of  greater  value  to  his  employer,  by  a  knowledge 
and  use  of  that  instrument.  His  question  was 
overheard  by  the  proprietor  of  a  large  establish- 
ment, who  took  occasion  to  reply  as  follows: 

"I  will  tell  you  what  good  an  indicator  did  at 
our  works.  Our  steam  engine  was  not  giving 
sufficient  power  for  our  business,  and  we  ex- 
pected to  be  obliged  to  procure  a  larger  one.  A 
neighbor  suggested  that  we  have  our  engine 
indicated  to  see  if  we  were  getting  the  best 
service  obtainable  from  it.  This  was  done,  and 
the  result  was,  that  when  the  valves  were  prop- 
erly adjusted  and  other  slight  changes  made, 
we  had  ample  power,  and  the  improved  condition 
of  the  engine  made  a  reduction  in  our  coal  bills 
during  the  following  year  of  $500." 


62  INDICATING    THE 

Another  case:  An  expert  engineer  was  called 
to  indicate  several  locomotives  just  completed 
by  one  of  our  prominent  locomotive  builders, 
who  had  in  use  a  large  Corliss  engine,  which  had 
been  running-  only  a  few  months.  When  the  loco- 
motives were  indicated,  the  proprietor  proposed 
that  the  indicator  be  applied  to  the  Corliss 
engine,  the  engineer  of  which  remarked:  "Guess 
you  '11  find  her  all  right,  as  she  's  running-  fine." 
\The  first  card  showd  that  nearly  all  the  -work 
ivas  being  done  at  one  end  of  the  cylinder.  The 
valves  were  chang-ed  and  a  great  improvement 
was  apparent  in  the  running-  of  the  engine, 
while  the  actual  consumption  of  coal  was  re- 
duced from  an  averag-e  of  3,370  pounds  per  day, 
before  the  chang-e  was  made,  to  2,338  pounds 
afterward. 

These  two  instances  are  valuable  in  showing 
"  the  g-ood  of  an  indicator." 

Items  of  Information  to  be  Obtained  by  the  Use 
of  the  Indicator. — The  arrang-ement  of  the  valves 
for  admission,  cut-off,  release  and  compression 
of  steam. 

The  adequacy  of  the  ports  and  passages  for 
admission  and  exhaust;  and  when  applied  to  the 
steam  chest,  the  adequacy  of  the  steam  pipes. 

The  suitableness  of  the  valve  motion  in  point 
of  rapidity  at  the  right  time. 

The  quantity  of  power  developed  in  the  cyl- 
inder, and  the  quantity  lost  in  various  ways:  by 
wire  drawing,  by  back  pressure,  by  premature 
release,  by  mal-adjustment  of  valves,  leakage, 
etc. 

It  is  useful  to  the  designers  of  steam  en- 
gines in  showing  the  distribution  of  horizontal 


STEAM     ENGINE.  63 

pressures  at  the  crank  pin,  through  the  momen- 
tum and  inertia  of  the  reciprocating- parts,  and  the 
angular  distribution  of  the  tangential  component 
of  the  horizontal  pressure;  in  other  words,  the 
rotative  effect  around  the  path  of  the  crank. 

Taken  in  combination  .with  measurements  of 
feed  water  and  the  condensation  and  measure- 
ment of  the  exhaust  steam,  with  the  amount  of 
fuel  used,  the  indicator  furnishes  many  other 
items  of  importance  when  the  economical  genera- 
tion and  use  of  steam  are  considered. 

For  every  one  of  these  purposes  it  is  import- 
ant that  the  diagram  traced  by  the  indicator 
should  truly  represent  the  path  of  the  piston  and 
the  pressure  exerted  on  both  sides  of  the  piston 
at  every  point  of  that  path. 

INDICATOR   DIAGRAMS. 

The  degree  of  excellence  to  which  steam 
engines  of  the  present  time  have  been  brought 
is  due  more  to  the  use  of  theindicator  than  to  any 
other  cause,  as  a  careful  study  of  indicator 
diagrams  taken  under  different  conditions  of 
load,  pressure,  etc.,  is  the  only  means  of  becom- 
ing familiar  with  the  action  of  steam  in  an  engine, 
and  of  gaining  a  definite  knowledge  of  the  vari- 
ous changes  of  pressure  that  take  place  in  the 
cylinder. 

An  indicator  diagram  is  the  result  of  two 
movements,  namely:  a  horizontal  movement  of 
the  paper  in  exact  correspondence  with  the 
movement  of  the  piston,  and  a  vertical  move- 
ment of  the  pencil  in  exact  ratio  to  the  pressure 
exerted  in  the  cylinder  of  the  engine;  con- 
sequently, it  represents  by  its  length  the  stroke 


64  INDICATING   THE 

of  the  engine  on  a  reduced  scale,  and  by  its 
height  at  any  point,  the  pressure  on  the  piston 
at  a  corresponding-  point  in  the  stroke.  The 
shape  of  the  diagram  depends  altogether  upon 
the  manner  in  which  the  steam  is  admitted  to 
and  released  from  the  cylinder  of  the  engine; 
the  variety  of  shapes  given  from  different  en- 
gines, and  by  the  same  engine  under  different 
circumstances,  is  almost  endless,  and  it  is  in  the 
intelligent  and  careful  measurement  of  these  that 
the  true  value  of  the  indicator  is  found,  and  no 
one  at  the  present  day  can  claim  to  be  a  competent 
engineer  who  has  not  become  familiar  with  the 
use  of  the  indicator,  and  skillful  in  turning  to 
practical  advantage  the  varied  information  which 
it  furnishes. 

A  diagram  shows  the  pressure  acting-  on  one 
side  of  the  piston  only,  during  both  the  forward 
and  return  stroke,  whereon  all  the  changes  of 
pressure  may  be  properly  located,  studied  and 
measured.  To  show  the  corresponding  press- 
ures on  the  other  side  of  the  piston,  another  dia- 
gram must  be  taken  from  the  other  end  of  the 
cylinder.  When  the  three-way  cock  is  used,  the 
diagrams  from  both  ends  are  usually  taken  on 
the  same  paper,  as  in  Fig.  9. 

ANALYSIS  OF  THE  DIAGRAM. 

The  names  by  which  the  various  points  and 
lines  of  an  indicator  diagram  are  known  and  des- 
ignated are  given  below,  and  their  significance 
fully  explained.  (See  Fig.  1.) 

The  closed  figure  or  diagram,  CD  E F  G  H, 
is  drawn  by  the  indicator,  and  is  the  result  of  one 
indication  from  one  side  of  the  piston  of  an 


STEAM    ENGINE.  65 

engine.  The  straight  line  A  B  is  also  drawn  by 
the  indicator,  but  at  a  time  when  steam  connec- 
tion with  the  engine  is  closed,  and  both  sides  of 
the  indicator  piston  are  subjected  to  atmospheric 
pressure  only. 

The  straight  lines  O  X,  O  ^and/TT,  when 
required,  are  drawn  by  hand  as  explained  below, 
and  may  be  called  reference  lines. 
Y 


H- 


B 


FIG.  1. 
DIAGRAM  LINES  EXPLAINED. 

The  admission  line  C  D  shows  the  rise  of 
pressure  due  to  the  admission  of  steam  to  the 
cylinder  by  the  opening-  of  the  steam  valve.  If 
the  steam  is  admitted  quickly  when  the  engine 
is  about  on  the  dead  center  this  line  will  be  nearly 
vertical. 

The  steam  line  D  E  is  drawn  when  the  steam 
valve  is  open  and  steam  is  being-  admitted  to  the 
cylinder. 

The  point  of  cut-off  E  is  the  point  where  the 
admission  of  steam  is  stopped  by  the  closing  of 
the  valve.  It  is  sometimes  difficult  to  determine 


66  INDICATING    THE 

the  exact  point  at  which  the  cut-off  takes  place. 
It  is  usually  located  where  outline  of  diagram 
changes  its  curvature  from  convex  to  concave. 

The  expansion  curve  E  F  shows  the  fall  in 
pressure  as  the  steam  in  the  cylinder  expands 
behind  the  moving-  piston  of  the  engine. 

The  point  of  release  F  shows  when  the  ex- 
haust valve  opens. 

The  exhaust  line  F  G  represents  the  loss  of 
pressure  which  takes  place  when  the  exhaust 
valve  opens  at  or  near  the  end  of  the  stroke. 

The  back  pressure  line  ^^showsthe  pressure 
against  which  the  piston  acts  during*  its  return 
stroke.  On  diagrams  taken  from  non-condens- 
ing engines  it  is  either  coincident  with  or  above 
the  atmospheric  line,  as  in  Fig.  1.  On  cards 
taken  from  a  condensing  engine,  however,  it  is 
found  below  the  atmospheric  line,  and  at  a  dis- 
tance greater  or  less  according  to  the  vacuum 
obtained  in  the  cylinder. 

The  point  of  exhaust  closure  H  is  the  point 
where  the  exhaust  valve  closes.  It  cannot  be 
located  very  definitely,  as  the  change  in  pressure 
is  at  first  due  to  the  gradual  closing  of  the  valve. 

The  compression  ctirve  H  C  shows  the  rise  in 
pressure  due  to  the  compression  of  the  steam 
remaining  in  the  cylinder  after  the  exhaust  valve 
has  closed. 

The  atmospheric  line  A  B  is  a  line  drawn  by 
the  pencil  of  the  indicator  when  its  connections 
with  the  engine  are  closed  and  both  sides  of  the 
piston  are  open  to  the  atmosphere.  This  line 
represents  on  the  diagram  the  pressure  of  the 
atmosphere,  or  zero  of  the  steam  gauge. 


STEAM    ENGINE.  67 

REFERENCE  LINES  EXPLAINED. 

The  zero  line  of  pressure,  or  line  of  absolute 
vacuum  OX,  is  a  reference  line,  and  is  drawn  by 
hand  14T\  pounds  by  the  scale,  below  and  parallel 
with  the  atmospheric  line.  It  represents  a  per- 
fect vacuum,  or  absence  of  all  pressure. 

The  line  of  boiler  pressure  J  K  v&  drawn  by 
hand  parallel  to  the  atmospheric  line  and  at  a 
distance  from  it,  by  the  scale  equal  to  the  boiler 
pressure  shown  by  the  steam  gauge.  The  differ- 
ence in  pounds  between  it  and  the  line  of  the  dia- 
gram D  E shows  the  pressure  which  is  lost  after 
the  steam  has  flowed  through  the  contracted 
passages  of  the  steam  pipes  and  the  ports  of  the 
engine. 

The  clearance  line  O  T  is  another  reference 
line  drawn  at  right  angles  to  the  atmospheric 
line  and  at  a  distance  from  the  end  of  the  dia- 
gram equal  to  the  same  per  cent  of  its  length  as 
the  clearance  bears  to  the  piston  travel  or  dis- 
placement. The  distance  between  the  clearance 
line  and  the  end  of  the  diagram  represents  the 
volume  of  the  clearance  and  waste  room  of  the 
ports  and  passages  at  that  end  of  the  cylinder. 

DERANGED  VALVE  MOTION. 

Fig.  2  shows  two  diagrams,  one  from  each 
end  of  the  cylinder  of  a  single-valve  high  press- 
ure engine.  This  valve  admits  the  steam  over 
its  ends  and  exhausts  inside.  The  derangement 
is  caused  by  the  valve  stem  being  too  long;  con- 
sequently, at  the  back  end  the  diagram  shows 
that  the  steam  was  admitted  late,  cut  off  early, 
exhausted  early  and  the  exhaust  valve  closed 
late,  so  that  there  is  little  or  no  compression. 


68  INDICATING    THE 

The  diagram  at  the  crank  end  shows  the  opposite 
defects,  viz.:  Steam  is  admitted  too  soon  and 
carried  too  far  on  the  stroke,  the  exhaust  valve 
is  opened  too  late  and  closed  too  soon  to  get  the 
steam  well  out  of  the  cylinder,  causing1  excessive 
back  pressure  —  even  greater  than  the  boiler 
pressure  as  shown  by  the  loop  at  the  top. 

To  remedy  this  derangement,  the  valve  stem 
should  be  shortened  by  the  screw  threads  at  one 
end.  It  may  then  be  found  that  the  steam  valve 


FIG.  2. 

opens  a  little  too  late  at  both  ends,  and  it  will 
therefore  be  necessary  to  turn  the  eccentric 
ahead  on  the  shaft  until  both  diagrams  resemble 
the  figures  shown  in  the  heaviest  lines. 

UNITS  OF  MEASUREMENT  AND  TECHNICAL  TERMS. 

All  substances  of  whatever  nature  are  meas- 
urable, and  their  measurements  are  referable 
to  some  established  unit,  to  be  properly  ex- 
pressed and  dealt  with.  An  intimate  knowledge 
of  some  of  these  is  indispensable  to  the  engineer; 
a  few  are  here  briefly  defined: 

The  unit  of  linear  measurement  is  the  inch  or 
one-twelfth  part  of  a  foot. 


STEAM    ENGINE.  69 

The  unit  of  superficial  measurement  is  the 
square  inch. 

The  unit  of so lid measurement'^  the  cubic  inch. 

The  unit  of  fluid  pressure  is  the  pound  avoir- 
dupois, consisting  of  7,000  grains. 

The  unit  of  elasticity,  or  the  pressure  exerted 
by  elastic  fluids,  is,  for  popular  use,  one  pound 
on  one  square  inch. 

The  unit  of  work  or  power  is  one  pound  lifted 
twelve  inches,  or  in  other  words,  one  pound  of 
force  acting-  through  one  foot  of  distance,  and  is 
called  the  foot-pound. 

Horse  Power. — The  standard  used  for  meas- 
uring- the  power  of  a  steam  engine  is  the  horse 
power.  It  was  originally  determined  by  James 
Watt  from  experiments  made  on  London  dray 
horses.  It  is  considerably  above  the  power  of 
an  ordinary  horse  and  is  now  simply  an  arbitrary 
standard.  It  is  equal  to  33,000  foot-pounds  ex- 
erted during-  one  minute  of  time,  or  550  foot- 
pounds during-  one  second.  As  a  foot-pound  is 
the  amount  of  work  done  in  raising  one  pound 
through  the  distance  of  one  foot,  an  equivalent 
amount  of  work  would  be  raising  half  a  pound 
two  feet,  or  twelve  pounds  one  inch. 

Indicated  horse  power  is  the  horse  power  of 
an  engine  as  found  by  the  use  of  a  steam  engine 
indicator,  and  is  thus  expressed:  I.  H.  P. 

Net  horse  power  is  the  indicated  horse  power 
of  an  engine,  less  the  horse  power  which  is  con- 
sumed in  overcoming  its  own  friction. 

Wire  drawing,  as  applied  to  steam,  is  the  re- 
ducing of  its  pressure,  due  to  its  flowing  through 
restricted  or  crooked  pipes  and  passages. 

Absolute  pressure  is  pressure  reckoned  from 


70  INDICATING    THE 

absolute  vacuum;  in  other  words,  it  is  the  press- 
ure of  any  fluid  as  shown  by  a  pressure  gauge, 
with  the  weight  or  pressure  of  the  atmosphere 
added  thereto. 

Initial  forward  pressure  in  a  cylinder  is  the 
pressure  acting  on  the  piston  at  or  near  the 
beginning  of  the  forward  stroke. 

Terminal  forward  pressure  is  the  pressure 
above  the  line  of  perfect  vacuum  that  would 
exist  at  the  end  of  the  stroke  if  the  steam  had 
not  been  released  earlier.  It  may  be  found  by 
continuing  the  expansion  curve  to  the  end  of  the 
diagram,  as  in  Fig.  1  at  F,  or  it  may  be  taken  at 
the  point  of  release.  This  pressure  is  always 
measured  from  the  line  of  perfect  vacuum,  hence 
it  is  the  absolute  terminal  pressure. 

Mean  effective  pressure  is  the  average  of  all 
the  steam  pressure  which  acts  on  one  side  of  the 
piston  to  move  it  forward,  less  all  the  steam 
pressure  which  acts  on  the  other  side  of  the 
piston  to  retard  it.  It  is  expressed  thus :  M.  E.  P. 

Piston  displacement  is  the  space  in  the  cylin- 
der swept  through  by  the  piston  in  its  travel. 
It  is  reckoned  in  cubic  inches,  and  is  found  by 
multiplying  the  net  area  of  the  piston  in  inches, 
by  the  length  of  stroke  in  inches,  allowance  being 
made  for  the  piston  rod. 

Clearance  is  all  the  waste  room  or  space  at 
either  end  of  the  cylinder,  between  its  head  and 
the  piston  when  on  a  dead  center,  including  the 
counterbore  and  the  ports,  up  to  the  face  of  the 
closed  valves. 

Sensible  heat  is  the  temperature  of  any  body, 
as  air,  water  or  steam,  which  may  be  measured 
by  the  thermometer. 


STEAM     ENGINE.  71 

Specific  heat  is  the  quantity  of  heat  required 
to  raise  one  unit  of  weight  of  the  substance 
through  one  degree  of  temperature,  measured 
in  thermal  units.-  When  the  pressure  remains 
constant  Regnault  found  the  specific  heat  for 
superheated  steam  to  be  0.4805  of  a  thermal 
unit. 

The  unit  of  heat,  or  thermal  unit,  is  the  quan- 
tity of  heat  required  to  raise  the  temperature  of 
one  pound  of  water  from  62°  to  63°  F. 

Mechanical  Equivalent  of  Heat. — It  has  been 
found  by  experiment  that  if  one  pound  of  pure 
water  at  62°  F.  be  raised  to  63°  F.,  that  energy 
is  exerted  equivalent  to  lifting  778  pounds  one 
foot  high,  or  one  pound  778  feet  high.  This 
energy  is  called  the  mechanical  equivalent  of  one 
thermal  unit  of  heat,  and  it  is  usually  designated 
by  the  letter  /  and  its  reciprocal,  or  Tfg,  by  A. 

Saturated  Steam. — When  steam  is  formed  in 
a  closed  vessel  in  contact  with  its  own  liquid,  it 
is  said  to  be  saturated,  and  it  will  have  a  certain 
definite  pressure  and  density  corresponding  to 
each  different  temperature.  If,  at  the  same 
time,  the  steam  contains  no  liquid  in  suspension, 
it  is  said  to  be  dry  and  saturated. 

Superheated  Steam. — If,  after  all  the  liquid 
has  been  converted  into  steam,  more  heat  be 
added,  the  temperature  will  rise  and  the  steam 
is  said  to  be  superheated,  because  its  tempera- 
ture will  be  greater  than  that  corresponding  to 
saturated  steam  of  the  same  pressure.  The 
amount  of  superheating  will  vary  according  to 
the  conditions  under  which  it  occurs — that  is  to 
say,  whether  the  volume  of  the  containing  vessel 
varies  or  remains  constant. 


72  INDICATING    THE 


CHAPTER  II. 

HOW  AND  WHERE  TO  ATTACH  THE  INDICATOR. 

The  indicator  should  be  attached  close  to  the 
cylinder  whenever  practicable,  especially  on 
high  speed  engines.  If  pipes  must  be  used  they 
should  not  be  smaller  than  half  an  inch  in  diame- 
ter, and  as  short  and  direct  as  possible ;  if  long- 
pipes  are  needed  they  should  be  slightly  larger 
than  half  an  inch,  and  covered  with  a  non-con- 
ducting material. 


FIG.  3. 

Diagrams  should  be  taken  from  both  ends  of 
the  cylinder  of  an  engine.  If  the  diagram  from 
one  end  is  satisfactory  it  is  not  safe  to  assume 
that  one  taken  at  the  other  end  will  be  equally 
so;  it  is  often  otherwise,  owing  to  the  varying 
conditions  usually  found;  the  lengths  of  thor- 
oughfares, the  points  of  valve  opening  and  clos- 
ing, and  the  lead,  are  variable  and  should  be 
carefully  adjusted  to  secure  the  best  results,  and 
this  can  only  be  done  through  the  instrumen- 
tality of  an  indicator. 

When  only  one  indicator  is  employed,  it  is 
generally  attached  to  a  three-way  cock  (Fig.  3), 


STEAM     ENGINE.  73 

which  is  located  midway  in  the  line  of  pipe,  con- 
necting- the  holes  at  either  end  of  the  cylinder; 
by  this  arrangement  diagrams  can  be  taken 
from  either  end  simply  by  turning-  the  handle  of 
the  three-way  cock.  In  such  a  case,  the  second 
diagram  should  be  taken  as  quickly  as  possible 
after  the  first,  so  as  to  be  under  like  conditions 
of  speed,  pressure  and  load. 

The  indicator  can  be  used  in  a  horizontal  posi- 
tion, but  it  is  more  convenient  to  take  diagrams 
when  it  is  in  a  vertical  position,  and  this  can  gen- 
erally  be -obtained,  when  attaching  to  a  vertical 
engine,  by  using  a  short  pipe  with  a  quarter  up- 
ward bend.  No  putty  or  red  lead  should  be  used 
in  making  any  joints,  as  particles  of  it  may  be 
carried  by  the  steam  into  the  indicator,  and 
great  harm  result  therefrom  ;  if  a  screw  fits 
loosely,  wind  into  the  threads  a  little  cotton 
waste,  which  will  make  a  steam  tight  joint.  The 
indicator  should  never  be  set  so  as  to  communicate 
with  thoroughfares  where  a  current  of  steam  will 
jlow  past  the  orifice  leading  to  the  indicator,  as  the 
diagrams  taken  under  such  conditions  would  be  of 
no  practical  value. 

The  cylinders  of  most  modern  steam  engines 
are  drilled  and  tapped  for  the  indicator  and  have 
plugs  screwed  into  the  holes,  which  can  readily 
be  removed  and  the  proper  indicator  connections 
inserted.  But  when  this  is  not  the  case,  the 
engineer  should  be  competent  to  do  it  under  the 
directions  here  given. 

When  drilling  holes  in  the  cylinder  the  heads 
should  be  removed  if  convenient,  so  that  one 
may  know  the  exact  position  of  the  piston,  the 
size  of  ports  and  passages,  and  be  able  to  remove 

(6) 


74  INDICATING    THE 

every  chip  or  particle  of  grit  which  might  other- 
wise do  harm  in  the  cylinder  or  be  carried  into 
the  indicator  and  injure  it.  When  the  heads  can- 
not be  taken  off,  it  can  be  arranged  so  that  a  little 
steam  may  be  let  into  the  cylinder,  when  the 
drill  has  nearly  penetrated  its  shell,  so  that  the 
chips  may  be  blown  outward,  care  being  taken 
not  to  scald  the  operator. 

Each  end  of  the  cylinder  should  be  drilled 
and  tapped  for  one-half-inch  pipe  thread.  The 
holes  must  always  be  drilled  into  the  clearance 
space,  at  points  beyond  the  range  of  the  piston 
when  at  the  end  of  the  stroke,  so  as  not  to  be  ob- 
structed by  it,  and  away  from  steam  passages,  to 
avoid  strong  currents  of  steam.  By  placing  the 
engine  on  a  dead  center,  it  is  easy  to  tell  how  much 
clearance  there  is,  and  the  hole  should  be  drilled 
into  the  middle  of  this  space;  the  same  process 
should  be  repeated  at  theotherendof  the  cylinder. 

On  horizontal  engines  the  most  common  prac- 
tice is  to  drill  and  tap  holes  in  the  side  of  the 
cylinder  at  each  end,  and  insert  short  half-inch 
pipes  with  quarter  upward  bends,  into  which  the 
indicator  cocks  may  be  screwed ;  on  some  hori- 
zontal engines  it  may  be  more  convenient  to  drill 
and  tap  into  the  top  of  the  cylinder  at  each  end, 
and  screw  the  cocks  directly  into  the  holes. 
On  vertical  engines,  for  the  upper  end  of  the 
cylinder  the  cock  may  be  screwed  into  the  upper 
head  or  cover,  and  for  the  lower  end,  into  the  side 
of  the  cylinder,  after  drilling  and  tapping  the 
necessary  hole.  It  is  preferable  to  drill  the  holes 
in  the  sides  of  a  cylinder  rather  than  the  heads, 
because  the  former  gives  better  results  and 
requires  less  pipe  and  fittings. 


STKAM     ENGINE.  75 

Before  deciding-  just  where  to  drill  the  holes 
it  is  wise  to  consider  all  the  conditionsof  the  case 
and  devise  the  whole  plan  for  indicating1  the 
engine. 

Sometimes  a  drum  motion  can  be  erected 
more  advantag-eousry  in  one  place  or  position  in 
the  engine  room  than  another,  or  one  kind  may 
be  better  adapted  for  a  given  place  than  another. 
Again,  the  type  of  engine  and  position  of  the 
steam  chest,  the  kind  of  cross-head  and  the  best 
means  for  attaching  to  it,  the  position  of  the 
eccentric,  its  rods  and  connections,  -all  should 
be  taken  into  account  when  determining- the  best 
places  to  drill  the  cylinder  and  locate  the  indica- 
tor, in  order  to  secure  a  proper  connection  with 
the  reducing  motion,  a  perfectly  free  passag-e  for 
steam  to  the  indicator  and  the  most  convenient 
access  to  the  instrument  for  taking  diagrams. 


76 


INDICATING    THK 


CHAPTER  III. 

THE   DRUM    MOTION. 

The  motion  of  the  paper  drum  may  be  derived 
from  any  part  of  the  engine  which  has  a  move- 
ment coincident  with  that  of  the  piston.  In 
general  practice  and  in  a  large  majority  of  cases 
the  cross-head  is  chosen  as  being-  the  most  relia- 
ble and  convenient  part, 
and  for  this  purpose  it  is 
drilled  and  tapped  for  an 
iron  stud  or  pin  to  be 
screwed  in  to  it.  This  stud 
should  be  long-  enough,  in 
most  cases,  to  reach  about 
six  inches  beyond  the 
outer  surface  of  the  cyl- 
inder. The  movement  of 
the  cross-head  must  be 
reduced  from  whatever  it 
actually  is,  to  about  three 
inches,  or  the  leng-th  of 
the  diagram  to  be  taken, 
FlG-  4-  and  this  reduced  motion 

must  be  in  exact  ratio  to  the  motion  of  the  piston. 
To  obtain  this  reduced  motion  a  variety  of 
means  may  be  employed,  any  one  of  which  calls 
forth  the  ingenuity  and  skill  of  the  engineer. 
The  reducing  lever  in  some  one  of  its  various 
forms  is  easily  made,  and  can  be  adapted  to  suit 
almost  any  conditions. 

The  slotted  lever  (Fig.  4)  is  a  common  form 
of  this  device,  and  answers  very  well  for  large 


STEAM     ENGINE. 


77 


and  quick  running-  engines.  It  should  be  made 
of  straight  grained  pine,  one  inch  or  more  in 
thickness,  about  six  inches  wide  at  the  top,  where 
there  is  a  hole  for  a  bolt,  and  tapering-  to  four 
inches  at  the  bottom,  where  there  is  a  slot  about 
six  inches  long-  and  of  the  same  width  as  the 
diameter  of  stud  in  the  cross-head,  which  gives 
it  a  vibrating  motion.  This  lever  is  suspended 
by  a  bolt  from  the  ceiling  or  from  a  truss  or 
frame  overhead  prepared  for  that  purpose,  in 
such  a  manner  as  to  permit  it  to  swing  edgewise 
and  parallel  with  the  guides. 
It  must  hang  plumb  when  the 
stud  in  the  cross-head  is  in  the 
slot  and  the  piston  is  at  mid-  c 
stroke;  in  this  position  the 
slot  should  extend  an  inch  or 
more  above  the  stud,  for  play. 

To  find  the  point  at  which 
to  attach  the  cord,  divide  the 
length  of  the  lever  by  the 
length  of  the  piston  stroke,  and 
multiply  the  quotient  by  the 
required  length  of  the  dia- 
gram, and  the  product  will  be  the  proper  distance 
from  the  pivot  to  the  point  of  attachment. 

The  slotted  lever  with  a  cord  arm,  which  can 
be  set  at  any  desired  angle  to  the  main  lever,  is 
shown  in  Fig.  5.  This  is  a  convenient  device 
when  it  is  found  necessary  to  attach  the  reduc- 
ing motion  to  the  floor,  which  may  be  done  by 
fastening  down  with  lag  screws  or  bolts  a  suit- 
able piece  of  timber,  to  which  the  lever  is  pivoted, 
so  that  it  will  vibrate  edgewise  with  the  move- 
ment of  the  engine.  It  may  also  be  attached 


FIG.  5. 


78 


INDICATING    THE 


overhead  in  the  same  manner  as  the  plain  slotted 
lever.  The  lever  must  stand  plumb  when  the 
piston  is  at  mid-stroke,  at  which  time  the  cord 
arm,  a,  must  be  fixed  at  such  an  angle  as  to  have 
the  cord,  c,  draw  at  right  angles  to  its  longitu- 
dinal axis,  and  in  the  plane  of  its  vibration;  the 
direction  of  the  cord  may  have  any  necessary 
angle  with  horizontal  line,  but  it  must  be  at  right 

angles  with  the  cord 
arm  at  mid-stroke. 
The  point  of  attach- 
ment for  the  cord  is 
found  by  the  same 
arithmetical  rule  as 
given  for  Fig.  4. 

The  Brumbo  pul- 
ley, shown  in  Fig.  6, 
is  another  form  of 
reducing  lever,  and 
one  more  generally 
used  by  engineers, 
especially  on  loco- 
{  1  motives.  It  can  be 

FIG.  6.  quickly  and  cheaply 

made,  and  can  be  used  on  almost  any  engine.  The 
swinging  lever,  E,  is  a  strip  of  pine  board  three 
or  four  inches  wide,  and  at  least  one  and  a  half 
times  as  long  as  the  piston  stroke.  It  is  sus- 
pended by  a  bolt  or  screw  from  a  frame  or  truss 
overhead,  constructed  for  that  purpose,  and  is 
connected  at  its  lower  end  by  the  wooden  link,  F, 
of  convenient  length  (say  about  one-half  the 
length  of  stroke)  to  the  usual  stud  or  pin  at- 
tached to  the  cross-head.  The  sector,  S,  also 
made  of  wood,  with  a  groove  in  its  lower  circular 


STEAM     ENGINE.  79 

edge  for  the  cord  to  run  in,  is  screwed  to  the 
upper  end  of  the  pendulum,  so  that  its  center 
will  exactly  coincide  with  the  center  of  the  bolt 
on  which  it  swing's.  The  radius  of  the  sector, 
which  is  necessary  to  give  the  proper  motion  to 
the  drum  to  obtain  the  desired  length  of  the 
diagram,  can  be  found  as  follows:  Divide  the 
length  of  the  lever  by  the  length  of  the  piston 
stroke,  and  multiply  the  quotient  by  the  length 
of  the  diagram  desired,  and  the  product  will  be  the 
required  radius,  all  the  terms  being  expressed 
in  inches.  For  example:  If  the  lever  is  thirty 
inches  long  and  the  piston  stroke  twenty  inches, 
and  we  wish  to  obtain  a  diagram  three  inches 
long,  we  have  30  inches  -*-  20  inches  =  1>£  inches; 
1>2  inches  X  3  inches  —  4j^  inches,  the  radius 
required  to  give  a  3-inch  diagram. 

When  the  conditions  are  favorable,  the  lever 
should  be  hung  so  that  it  will  swing  in  a  vertical 
plane,  parallel  with  the  guides  and  in  line  with 
the  indicator,  as  this  arrangement  is  the  most 
simple,  and  the  use  of  guide  pulleys  is  avoided. 
It  is  not  absolutely  necessary,  however,  that  the 
lever  shall  swing  in  a  vertical  plane,  but  it  may 
swing  in  a  plane  at  any  angle  thereto,  where  the 
conditions  require  it.  In  such  cases,  a  man's 
ingenuity  and  inventive  faculty  must  aid  him.  A 
link  made  of  a  thin  strip  of  steel,  that  will  twist 
a  little,  is  in  some  cases  very  convenient. 

When  the  cross-head  is  at  mid-stroke  the  lever 
must  hang  plumb,  and  the  pin  which  connects  its 
lower  end  to  the  link  must  be  as  much  below  the 
line  of  motion  of  the  stud  in  the  cross-head  H, 
as  it  sweeps  above  that  line  at  either  end  of  the 
stroke.  See  cut  for  illustration  of  this  point, 


80 


INDICATING    THE 


which  is  important.  The  cord  must  lead  from 
the  sector  in  about  the  same  plane  with  its  swing*. 
Carrying  pulleys  should  be  avoided  whenever 
possible,  but  whatever  number  is  necessary 
should  be  firmly  placed.  The  swing-ing-  arm  of 
the  guide  pulley  on  the  indicator  should  always 
be  adjusted  in  the  direction  from  which  the  cord 
is  received.  Some  engines  are  furnished  with  a 
drum  motion  of  this  kind,  made  of  steel  with 
nicely  fitted  joints,  which  can  be  readily  attached 
to  the  engine,  and  are  very  convenient  to  use. 


FIG.  7. 

The  pantograph,  illustrated  in  Fig.  7,  is 
another  style  of  reducing  motion.  Although 
theoretically  it  gives  a  perfect  motion,  owing  to 
its  many  joints  it  may  soon  become  shaky  and 
give  erroneous  results,  unless  it  is  very  nicely 
made  and  carefully  used.  When  the  indicator 
is  applied  to  the  side  of  the  cylinder  the  panto- 
graph works  in  a  horizontal  plane.  The  pivot  end 
B  rests  on  a  post  or  other  support  set  opposite 
to  the  middle  of  the  guides,  and  the  working  end 
A  receives  motion  from  the  cross-head — to  which 


STEAM     ENGINE.  81 

it  is  attached  by  a  suitable  iron  with  a  hole  drilled 
in  it  for  the  stud  A  to  work  in.  By  ad j  usting  the 
support  for  the  pivot  end  to  the  proper  height  and 
at  a  proper  distance  from  the  guides,  the  cord 
may  be  carried  directly  from  the  pin  E  to  the 
indicator  without  the  need  of  carrying-  pulleys. 

The  reducing  -wheel  is  another  device  for  giv- 
ing the  proper  motion  to  the  paper  drum.  Al- 
though old  in  principle,  and  as  formerly  made 
not  highly  approved  by  experienced  engineers, 
this  style  is  now  coming-  into  more  g-eneral  use, 
and  the  superior  manner  in  which  it  is  desig-ned 
and  constructed  seems  to  warrant  this  chang-e — 
especially  on  short-stroke  engines  which  re- 
quire only  a  short  cord.  Its  portability  and  con- 
venience of  application  also  tend  to  make  it  a 
favorite,  especially  with  young  engineers.  It  is 
usually  clamped  to  the  frame  of  the  engine,  in  a 
direct  line  from  the  indicator  to  the  stud  in  the 
cross-head,  thus  avoiding  the  need  of  guide  pul- 
leys. This  is  considered  the  only  practical  drum 
motion  for  an  oscillating  engine. 

Whatever  drum  motion  mechanism  is  used, 
its  accuracy  can  be  easily  tested  in  the  following 
manner :  Lay  off  on  the  guides,  points  at  one- 
quarter,  one-half  and  three-quarters  of  the 
stroke.  Connect  the  indicator  with  the  drum  mo- 
tion in  the  same  manner  as  for  taking  diagrams. 
When  the  cross-head  is  on  either  dead  center, 
touch  the  pencil  to  the  paper  and  make  a  vertical 
mark,  and  in  the  same  way  make  vertical  marks 
when  the  cross-head  reaches  each  successive 
quarter  point  on  the  guides.  If  the  marks  are 
exactly  at  fourths  on  the  card,  the  motion  of  the 
cross-head  has  been  accurately  reduced. 


82 


INDICATING    THE 


The  directions  here  given  for  constructing 
and  arranging-  drum  motions  are  general;  special 
cases  may  require  modification  of  the  forms  and 
special  adaptation  of  the  means  here  described, 
all  of  which  call  forth  the  ingenuity  and  skill  of 
the  engineer. 

Fig.  8  X  shows  a  pantograph  device  at  mid- 
stroke.  This  is  made  of  bar  iron  nicely  riveted 
together.  The  indicator  cord  may  be  attached 
at  b.  The  end  a  is  attached  to 
a  pin  on  the  cross-head.  The 
fixed  fulcrum  is  at  c.  a,  b  and 
c  must  always  lie  in  the  same 
straight  line,  and  e  d,  b  n,  par- 
allel and  equal  to  f  g.  Also, 
af  :  nf=  stroke  of  piston  to 
length  of  indicator  diagram. 

Fig.  8  Y  is  a  device  used  at 
the  Massachusetts  Institute  of 
Technology.  f\<$>  a  rod  mov- 
ing in  a  slide  parallel  to  the 
piston  rod.  Link  b  d  is  at- 
tached toy,  and  link  a  e  to  the 
cross-head.  «,  b  and  c  must 
always  lie  in  the 
same  straightline. 


stroke  of  piston  to 
length  of  indi- 
cator  diagram. 
The  cord  is  hook- 
ed on  a  pin  at^;  it 
is  well  to  have  a 
pin  for  each  indi- 
cator  used. 


STEAM     ENGINE.  83 

Fig-.  8  Z  is  a  device  by  Armand  Stevart  for 
long-  strokes,  a  and  b  are  fixed  ends  of  cord 
wrapped  around  pulley  D.  Indicator  cord  is 
attached  to  small  pulley  d  and  passes  around 
g-uide  pulley  e.  D  and  <^are  attached  to  cross- 
head.  Dia.  D  -*-  dia.  d  =  stroke  piston  -*-  the 
difference  between  stroke  of  piston  and  leng-th 
of  card. 


84  INDICATING    THE 


CHAPTER  IV. 

HOW    TO    TAKE   DIAGRAMS. 

When  the  indicator  has  been  placed  in  posi- 
tion and  a  correct  drum  motion  obtained,  it  is  next 
necessary  to  adjust  the  length  of  the  cord  so  that 
the  drum  will  not  strike  the  stops  at  either  ex- 
treme of  its  rotation.  Find  about  the  length  of 
cord  required  and  make  a  loop  at  the  end,  so 
that  when  the  hook  on  the  short  piece  of  cord 
connected  with  the  indicator  is  hooked  in,  the 
cord  will  be  a  little  too  long.  Take  up  the  extra 
length  by  tying  knots  in  the  cord  until  the  drum 
rotates  without  striking  either  stop.  This 
method  may  seem  rather  primitive,  but  it  has 
been  adopted  by  many  of  our  best  engineers 
after  trying  the  various  devices  for  shortening 
the  cord. 

The  paper  or  card  should  be  wrapped 
smoothly  around  the  drum ;  have  the  two  lower 
edges  come  evenly  together  as  they  meet  after 
being  passed  under  the  clip;  when  in  this  posi- 
tion, the  paper  may  be  slipped  down  as  far  as 
the  shoulder  in  the  clip;  a  little  practice  will  en- 
able one  to  do  this  with  facility. 

After  the  cord  is  adjusted  and  a  paper 
wrapped  on  the  drum,  open  the  indicator  cock 
and  allow  the  piston  to  play  until  the  instrument 
has  been  thoroughly  warmed  by  the  steam,  then 
gently  press  the  pencil  on  the  paper  by  the 
wooden  handle.  After  the  pencil  has  remained 
on  the  paper  during  one  or  more  revolutions, 
draw  it  back,  close  the  cock  and  again  gently 


STEAM     ENGINE.  85 

press  the  pencil  on  the  paper  and  take  the  at- 
mospheric line. 

The  pressure  of  the  pencil  on  the  paper  can 
be  adjusted  by  screwing-  the  handle  in  or  out, 
so  that  when  it  strikes  the  stop  there  will  be 
just  enough  pressure  on  the  pencil  to  give  a 
distinct  fine  line.  The  line  should  not  be  heavy, 
as  the  friction  necessary  to  draw  such  a  line  is 
sufficient  to  cause  errors  in  the  diagram. 

After  the  diagram  has  been  taken  disconnect 
the  cord,  to  avoid  any  unnecessary  wear  on  the 
drum. 

On  locomotives  and  engines,  the  speed  of 
which  is  so  great  that  it  is  difficult  to  hook  in  the 
loop,  arrangements  can  easily  be  made  so  this 
will  not  have  to  be  done.  At  the  further  end  of 
the  arc  on  the  Brumbo  pulley  insert  an  ordinary 
screw  eye.  Drive  another  screw  eye  firmly  into 
a  small  hole  drilled  in  the  center  of  the  end  of 
the  bolt  on  which  the  bar  swings.  The  cord  from 
the  indicator  can  then  be  carried  through  the  eye 
at  the  end  of  the  arc,  and  then  through  the  eye 
in  the  end  of  the  bolt  and  back  to  some  conven- 
ient point  near  the  instrument  where  it  can  be 
easily  reached  by  the  operator.  Connect  the  cord 
with  the  instrument  and  draw  it  through  the 
eyes  until  the  drum  will  not  strike  the  stops  at 
its  extreme  positions.  Then  at  the  point  of  the 
cord  just  before  the  eye  at  the  end  of  the  arc,  tie 
a  small  ring.  When  the  cord  is  drawn  taut  by 
the  operator,  the  ring  stops  the  cord  when  it  has 
been  drawn  through  just  enough  to  give  the 
proper  motion  to  the  drum.  As  soon  as  the 
diagram  and  atmospheric  line  have  been  taken, 
slacken  the  cord  and  the  drum  will  stop.  This 


86  INDICATING    THE 

arrangement  is  very  convenient  on  locomotives, 
as  the  cord  can  be  drawn  taut  with  one  hand 
while  the  diagram  is  taken  with  the  other. 

Make  notes  on  the  card  of  as  many  of  the  fol- 
lowing- facts  as  possible:  The  day  and  hour  of 
taking-  the  diagram;  the  kind  of  engine  from 
which  the  diagram  is  taken,  which  end  of  the 
cylinder  and  which  engine,  if  one  of  a  pair ;  the 
diameter  of  the  cylinder,  the  leng-th  of  the  stroke, 
the  diameter  of  the  piston  rod,  the  number  of 
revolutions  per  minute  and  the  position  of  the 
throttle;  the  atmospheric  pressure;  the  steam 
pressure  at  the  boiler  and  at  the  engine,  by  the 
g-aug-e ;  the  vacuum  by  the  g-aug-e  on  condenser 
and  the  temperature  of  the  feed  at  the  boiler;  if 
the  engine  is  compound,  the  pressure  in  the  re- 
ceiver; the  scale  of  the  spring-  used  in  the  indi- 
cator; the  volume  of  the  clearance  at  each  end 
of  the  cylinder,  and  what  per  cent  of  the  piston 
displacement  each  of  these  volumes  is.  (Direc- 
tions for  ascertaining-  the  volume  of  the  clearance 
and  what  per  cent  that  volume  is  of  the  piston 
displacement,  are  given  on  pag-es  97  to  100.) 

It  is  often  useful  to  make  notes  of  special 
circumstances  of  importance,  such  as  a  descrip- 
tion of  the  boiler,  the  diameter  and  leng-th  of  the 
steam  and  exhaust  pipes,  the  temperature  of  the 
feed  water,  the  quantity  of  water  consumed  per 
hour,  etc. 

On  a  locomotive,  note  the  time  of  passag-e 
between  mile  posts  in  minutes  and  seconds, 
from  which,  when  the  diameter  of  the  drivers  is 
known,  the  number  of  revolutions  per  minute 
may  be  calculated.  Note  also  the  position  of 
the  throttle  and  the  link,  the  size  of  the  blast 


STEAM    ENGINE. 


87 


s 


a     ^ 

i8    ^ 


8 

R 


s; 
g 

.9 


r^>       ^> 

I 

Co 


'So 


is    "  !»: 


$•*  r*  r^  O 

^  ,;2  rt  <U  *+-« 

«  1  '1  S  c 

rt  >  ^  v> 

?  •§  1 1 1 

1 1 1 1 S 

5-i  _i  OJ  S  O 


C  C  rt 

cti  rt  3 

0  3  3 

O  5  rt 

ct 

u 


>  rt  ^  e 

^  ^  e  £ 


G     V 


be  .2    § 

.2  •£  ° 


orifice,  the  weight  of  the  train,  and  the  gradient. 

On  diagrams  from  marine  engines,  note,  in 

addition  to  the  general  facts,  the  speed  of  the 


88  INDICATING    THE 

ship  in  knots  per  hour,  the  direction  and  force 
of  the  wind,  the  direction  and  state  of  the  sea, 
the  diameter  and  pitch  of  the  screw,  the  kind  of 
coal,  the  amount  consumed,  and  the  ashes  made 
per  hour. 


STEAM     ENGINE.  89 


CHAPTER  V. 

HOW    TO    FIND    THE    POWER    OF    AN    ENGINE. 

To  find  the  power  actually  exerted  within  the 
cylinder  of  a  steam  engine,  it  is  necessary  to 
ascertain  separately  three  factors  and  the  product 
of  their  continued  multiplication.  These  factors 
are:  The  net  area  of  the  piston,  designated  by 
the  letter  a;  the  mean  velocity  or  speed  of  the 
piston,  designated  by  5;  and  the  mean  effective 
pressure  urging-  the  piston  forward,  desig-nated 
by  M.  E.  P. 

The  Piston  Area. — This,  at  the  back  end,  is 
the  same  as  the  area  of  cross-section  of  the  cyl- 
inder; at  the  crank  end  it  is  the  same,  less  the 
area  of  cross-section  of  the  piston  rod.  These 
areas  may  be  found  from  their  diameters  in  a 
table  of  the  areas  of  circles,  or  be  computed  by 
multiplying-  the  square  of  the  diameter  in  inches 
by  the  approximate  number  0.7854. 

The  Mean  Piston  Speed. — The  mean  of  the 
constantly  varying-  speed  of  the  piston  is  found 
by  multiplying-  twice  the  leng-th  of  the  stroke 
measured  in  feet,  by  the  number  of  revolutions 
of  the  crank  shaft  per  minute,  which  should  be 
carefully  ascertained  by  taking-  the  mean  of 
many  counting's,  or  the  reading's  of  a  speed 
counter  during-  a  considerable  time.  The  mean 
piston  speed  will  be  expressed  in  terms  of  feet 
per  minute. 

7^he  Mean  Effective  Pressure. —  There  are 
several  approximate  methods  for  computing- 
the  mean  effective  pressure,  one  of  which  is  to 


90 


INDICATING    THB 


divide  the  diagram  into  ten  equal  parts,  as 
shown  in  Fig*.  9.  Then  through  the  points  of 
division  draw  lines,  which  are  called  ordinates, 
at  right  angles  to  the  atmospheric  line.  The 
mean  heights  or  pressures  of  the  small  areas 
thus  formed  are  indicated  by  the  dotted  lines 
midway  between  the  ordinates. 

The  mean  effective  pressure  of  the  whole  (of 
each)  diagram  may  now  be  found  by  measuring 
(on  the  dotted  lines)  the  mean  pressure  in  each 
of  the  small  areas  with  the  scale  corresponding 
to  the  spring  used  in  taking  the  diagram. 


FIG.  9. 


Diagrams  from  Hartford  engine.  Cylinder,  16X24  inches.    Boiler  pressure, 

87  pounds.     Vacuum  per  gauge,  23l/2  inches.    130 

revolutions  per  minute. 

The  sum  of  these  mean  pressures,  divided  by 
10,  the  number  of  divisions,  will  give  the  mean 
effective  pressure  sought,  in  pounds  per  square 
inch. 

If  a  diagram  has  many  irregularities  of  out- 
line, it  may  be  necessary  to  divide  it  into  twenty 
equal  divisions  to  insure  a  correct  measurement 
of  the  pressures;  in  such  a  case  we  divide  the 
sum  of  the  pressures  by  20  instead  of  10.  In 


STEAM     ENGINE. 


91 


other  cases,  when  irregularities  occur  only  in  a 
part  of  a  diagram,  it  is  only  necessary  to  subdi- 
vide one  or  more  of  the  ten  divisions  to  insure 
greater  accuracy  in  that  part;  in  such  £  case  we 
must  measure  the  pressure  in  each  subdivision 
and  divide  their  sum  by  2  to  get  the  mean  press- 
ure of  that  division.  (See  Fig.  11  for  a  full  illus- 
tration of  this  method.) 

If  the  scale  is  not  at  hand  the  heights  of  the 
divisions  may  be  pricked  or  marked  off  on  a  strip 
of  paper,  one  after  the  other  continuously  until 
all  are  measured;  then  the  distance  from  the  end 


FIG.  10. 

of  the  strip  to  the  last  mark  will  represent  the 
sum  of  all  the  measurements,  which  can  be 
measured  in  inches  with  an  ordinary  rule.  This 
quantity,  divided  by  the  number  of  divisions  in 
the  diagram — or  diagrams,  if  there  are  two — and 
multiplied  by  the  scale  of  the  spring  used,  will 
give  the  average  of  mean  effective  pressure,  the 
same  as  by  the  other  method. 

When  there  is  a  loop  in  the  diagram,  as  in  Fig. 
10,  the  area  inclosed  in  the  loop  should  be  sub- 
tracted from  the  other  part,  as  it  represents  loss 
of  efficiency. 

The  quickest  and  most  accurate  method  for 


92  INDICATING   THE 

measuring'  the  diagram  and  finding  the  mean 
effective  pressure  is  by  the  use  of  Amsler's 
Polar  planimeter.  With  careful  manipulation, 
the  planimeter  will  give  the  exact  area  of  a 
diagram  in  square  inches  and  decimal  parts 
thereof,  to  hundredths  of  a  square  inch,  and  the 
tedious  process  of  dividing-  the  diagram  into 
equal  parts  and  measuring  their  average  press- 
ures or  heights,  with  the  liability  of  making 
errors,  is  avoided. 

Measure  the  diagram  with  the  planimeter,  as 
directed  in  Chapter  VII.  Divide  the  number  of 
square  inches  area  thus  found  by  the  length  of  the 
diagram,  expressed  in  inches  and  decimals,  and 
the  result  will  be  the  average  heig"ht  of  the  dia- 
gram. Multiply  this  average  height  by  the 
scale  corresponding  to  the  spring  used  in  taking 
the  diagrams,  and  the  result  will  be  the  mean 
effective  pressure.  It  is  better  to  multiply  first 
and  divide  afterward,  to  avoid  troublesome  frac- 
tions. (A  description  of  the  planimeter  and  full 
directions  for  its  use  on  indicator  diagrams  are 
given  in  Chapter  VII,  Part  II,  and  Chapters  X 
and  XI,  Part  III.) 

Fig.  11  illustrates  two  diagrams  divided  first 
into  ten  equal  spaces,  and  then  each  end  space 
subdivided  so  as  to  more  accurately  measure 
those  parts  of  each  in  which  the  greatest  irreg- 
ularities occur.  Observe  that  the  pressures 
or  heights  of  the  subdivisions  of  each  end  space 
are  measured,  and  the  sum  of  these  measure- 
ments divided  by  2  to  get  the  mean  pressure 
or  height  of  that  one  of  the  ten  spaces. 

The  pressures  of  Diagram  No.  1,  as  meas- 
ured by  the  scale,  are  set  in  a  column  on  the  left, 


STEAM    ENGINE. 


93 


DIAGRAM  No.  1 
Pressures. 


DIAGRAM  No.  2 
Pressures. 


FIG.  11. 

HEIGHTS  OF  DIVISIONS  MEASURED  ON  A  STRIP  OF  PAPER. 
DIAGRAM  No.  1.  DIAGRAM  No.  2. 

10)11.95  in.  Divide  by  10  10)11.93  in. 


1.195 

50 


M.E.P.  59.750 


Multiply  by  proper  scale. 


1.193 

50 


M.  E.  P.  59.650 


PLANIMETER  MEASUREMENTS. 

DIAGRAM  No.  1.  DIAGRAM  No.  2. 

Square  inches,      4.42  Square  inches,       4.46 

Length,  3.72  Length,  3.73 

Average  height,  1.188  Average  height,    1.195 

M.  E.  P.  59.4  Ibs.  M.  E.  P.  59.75  Ibs. 


94  INDICATING    THE 

while  those  of  No.  2  are  set  in  a  column  on  the 
right.  The  sum  of  each  column  divided  by  10 
gives  the  M.  E.  P.  of  that  diagram. 

The  heights  of  Diagram  No.  1,  marked  off  on 
a  slip  of  paper  continuously,  measure  11.93 
inches,  while  those  of  No.  2  measure  11.95 
inches;  these  quantities,  divided  by  10  and  mul- 
tiplied by  50,  give  the  M.  E.  P.  of  each  diagram 
respectively,  and  if  accurately  measured,  will 
be  the  same  as  found  by  the  scale. 

These  diagrams,  when  measured  by  the 
planimeter,  give  results  which  are  substantially 
the  same  as  found  by  the  approximate  methods. 
These  results  are  given  at  the  bottom  of  page 
93  with  Fig.  11. 

Having  now  obtained,  by  one  of  the  several 
methods  given  above,  our  three  factors  men- 
tioned at  the  beginning  of  this  chapter,  viz.: 

a  =  mean  net  area  of  piston  in  square  inches. 

5  =  mean  speed  of  piston  in  feet  per  minute. 

p  =  mean  effective  pressure  in  pounds  on 
each  square  inch  of  the  piston — the  product  of 
their  continued  multiplication  will  give  the  indi- 
cated power  of  the  engine  in  foot-pounds  per 
minute;  and  this  product  divided  by  33,000, 
which  is  the  conventional  number  of  foot-pounds 
in  one  horse  power,  will  give  a  quotient  equal  to 
the  indicated  power  of  the  engine  in  indicated 
horse  power,  commonly  designated  by  the  initial 
letters  I.  H.  P. 

Thus  :     I.  H.  P.  =  ^X_£X/  or  asP 
33,000          33..  000 

When  there  are  a  number  of  diagrams  taken 
from  the  same  engine  to  be  worked  up,  the  cal- 
culations may  be  simplified  by  multiplying  the 


STEAM     ENGINE.  95 

area  of  the  piston  by  twice  the  length  of  the 
stroke,  and  dividing-  the  result  by  33,000.  This 
gives  the  "constant  of  the  engine,"  that  is,  the 
power  that  would  be  developed  at  one  revolution 
per  minute  with  one  pound  mean  effective  press- 
ure. Multiply  this  constant  by  the  number  of 
revolutions  per  minute,  and  then  by  the  mean 
effective  pressure,  and  the  product  will  be  the 
I.  H.  P. 

If  the  number  of  revolutions  is  the  same  for 
several  diagrams,  as  is  frequently  the  case  with 
stationary  engines,  the  calculation  may  be  still 
further  simplified  by  multiplying1  the  "constant 
of  the  engine"  by  the  number  of  revolutions 
per  minute.  This  will  give  the  "horse  power 
constant,  "  or  the  horse  power  developed  per 
pound  M.  YJ.  P.  Multiply  the  horse  power 
constant  by  the  M.  E.  P.,  and  the  product  will 
be  the  indicated  horse  power  (I.  H.  P.). 


96  INDICATING    THK 


CHAPTER  VI. 

THE   HYPERBOLIC    CURVE. 

This  curve  is  frequently  applied  to  indicator 
diagrams  for  the  purpose  of  comparing-  it  with 
the  expansion  curve  as  drawn  by  the  indicator, 
and  if  it  coincides  very  nearly,  this  fact  may 
generally  be  taken  as  evidence  tending-  to  show 
that  the  steam  and  exhaust  valves  of  the  engine 
are  properly  closed  and  the  piston  tight. 

Without  going  into  any  discussion  regarding 
condensation  and  re-evaporation  in  steam  engine 
cylinders,  it  is  a  well  known  fact  that  indicator 
diagrams,  taken  from  large  engines,  properly 
made  and  in  good  order,  show  expansion  curves 
which  are  close  approximations  to  the  hyperbola. 

Before  this  curve  can  be  drawn,  it  is  neces- 
sary to  ascertain  the  capacity  of  the  clearance  or 
waste  room;  that  is,  all  the  space  between  the 
cylinder  heads  and  the  piston  at  each  dead  cen- 
ter, including  the  counterbore  and  the  ports  up 
to  the  face  of  the  closed  valves. 

There  are  several  ways  of  finding  this:  One, 
by  direct  calculation  from  sectional  drawings, 
when  accurate  drawings  can  be  obtained; 
another,  by  putting  the  engine  at  dead  center 
with  valves  closed,  and  then  filling  the  clearance 
space  with  water,  which  has  been  carefully 
weighed  in  a  convenient  vessel,  then  weighing 
what  is  left;  and  the  difference  between  the 
weight  of  the  whole  and  the  remainder  is  the 
weight  of  water  required  to  fill  the  clearance 
space.  From  this  the  number  of  cubic  inches 


STKAM     KNGINE.  97 

occupied  by  the  water  may  be  computed.  At 
ordinary  temperatures  (60°  to  75°  F.),  for  all 
practical  purposes,  we  may  call  the  weight  of 
one  cubic  inch  of  water  0.036  pounds,  and  27.8 
cubic  inches  of  water  equal  to  one  pound. 
Then  the  number  of  pounds  of  water,  divided 
by  0.036  or  multiplied  by  27.8,  will  give  the 
number  of  cubic  inches.  If  accurate  scales  for 
weig-hing-  the  water  are  not  at  hand,  it  can  be 
carefully  measured  in  a  quart  or  pint  measure, 
and  the  number  of  cubic  inches  found  directly. 
A  g-allon  contains  231  cubic  inches,  a  quart  57.75 
and  a  pint  28.875  cubic  inches. 

The  volume  of  the  clearance  will  rarely  be 
alike  at  the  two  ends  of  the  cylinder,  therefore 
the  number  of  cubic  inches  in  the  clearance  at 
each  end  must  be  divided  by  the  net  area  of  the 
piston  at  its  own  end;  that  is,  the  number  of 
cubic  inches  in  the  clearance  at  the  end  nearest 
the  crank  must  be  divided  by  the  number  of 
square  inches  in  the  cross-section  of  the  cyl- 
inder, less  the  number  of  square  inches  in  the 
cross-section  of  the  piston-rod;  and  the  number 
of  cubic  inches  in  the  clearance  at  the  end 
farthest  from  the  crank  must  be  divided  by 
the  number  of  square  inches  in  the  cross-section 
of  the  cylinder.  The  quotient  in  each  case  will 
be  the  leng-th  of  clearance  at  the  respective  ends 
of  the  cylinder,  expressed  in  inches. 

It  is  convenient  to  have  the  leng-th  of  the 
clearance  expressed  as  a  fraction  of  the  piston 
displacement  or  stroke  of  the  piston.  To  ob- 
tain this  fraction,  divide  the  number  of  cubic 
inches  in  volume  of  clearance  by  the  number  of 
cubic  inches  in  the  volume  swept  through  by  the 


98  INDICATING    THE 

piston  at  each  end  separately,  taking*  care  to 
allow  for  the  volume  occupied  at  one  end  by  the 
piston  rod,  and  the  quotient  will  be  the  decimal 
fraction  that  the  clearance  space  is  of  the  volume 
swept  throug-h  by  the  piston.  In  this  instance 
(Fig-.  12)  it  is  found  to  be  .16  inches. 

Fig1.  12  illustrates  a  g"ood  method  for  locating- 
points  in  the  hyperbola  throug-h  which  the  curve 
may  be  drawn. 

First,  draw  the  zero  line    V,  at  the  proper 


Id  --  v  --  V-   _^__   --  \i  __  \f  __  L    _ 


U  —  -  --  ^Length  of2jta.gro.7n    3.90 
FiG.  12. 

distance,  viz.,  14-jV  pounds  by  the  scale  below 
and  parallel  with  the  atmospheric  line;  next, 
draw  the  clearance  line  O,  as  computed,  .16  of 
an  inch  from  the  end  of  the  diagram;  next,  locate 
the  point  of  cut-off  X,  and  draw  the  perpen- 
dicular line  number  3  through  it;  next,  divide 
the  space  between  this  line  and  the  clearance 
line  into  three  equal  parts;  then,  taking-  one  of 
these  parts  for  a  measure,  point  off,  on  the 
vacuum  line,  equal  spaces  toward  the  left  hand 
until  one  or  more  falls  beyond  the  end  of  the 


STEAM     ENGINE.  99 

diagram  as  shown,  and  erect  perpendicular  lines 
from  each  point.  These  lines  are  called  ordioates 
and  numbered  consecutively  1,  2,  3,  4,  etc., 
beginning-  with  the  one  next  to  the  clearance 
line.  It  is  well  to  bear  in  mind  the  fact  that 
vertical  distance  on  a  diagram  represents  press- 
ure, and  horizontal  distance  volume. 

In  this  case  we  have  started  the  hyperbola 
from  the  point  of  cut-off  X,  and  its  course  is 
indicated  by  the  short  lines  drawn  throug-h  the 
ordinates  a  little  above  the  actual  curve,  with 
their  calculated  pressures  written  above;  the 
actual  pressures  of  the  expansion  curve  are 
written  below  it.  The  properties  of  the  hyper- 
bola are  such,  that  if  the  distance  of  the  point 
Jf  from  the  clearance  line  O  be  multiplied  by  the 
heig-ht  of  X  from  the  zero  line  V,  the  heig-ht  of 
any  other  point  in  the  curve  can  be  found  by 
dividing-  this  product  by  its  distance  from  the 
clearance  line.  And  on  this  principle  we  proceed 
to  locate  points  on  the  ordinates  throug-h  which 
our  hyperbola  will  run. 

We  find  the  pressure  at  the  point  of  cut-off 
to  be  121  pounds,  with  a  volume  which  we  call 
3,  because  there  are  three  spaces  or  volumes 
between  it  and  the  clearance  line.  Then,  121 X 
3  =  363,  which  is  our  dividend  for  all  the  other 
volumes.  Therefore  the  height  at  which  the 
hyperbola  will  cut  ordinate  4  will  be  determined 
by  dividing-  363  by  4,  which  is  90.8  (it  is  un- 
necessary to  carry  the  division  beyond  one  deci- 
mal), and  of  ordinate  5,  72.6;  of  ordinate  6,  60.5; 
and  so  on  to  the  end.  At  ordinate  12  we  find 
that  the  hyperbolic  and  the  actual  curves  practi- 
cally coincide.  In  like  manner  we  may  extend 


100  INDICATING    THE 

the  curve  to  the  right:  363  -*-  2  =  181  pounds, 
which  would  be  the  pressure  if  the  steam  were 
compressed  up  to  two  volumes.  If  desired, 
the  hyperbolic  curve  can  be  started  just  before 
the  point  of  release,  and  projected  in  the  op- 
posite direction  by  the  same  method. 

Instead  of  using-  figures,  which  stand  for 
pressures  or  volumes  of  steam,  to  locate  the 
hyperbola,  as  in  this  instance,  the  distances 
from  the  base  and  perpendicular  lines  of  any 
point  may  be  expressed  in  inches  and  decimal 
parts,  with  the  same  result. 

A  quick  way  to  draw  the  hyperbola  is  to  take 
the  whole  distance  between  ordinate  3  and  the 
clearance  line  as  a  measure,  and  set  off  equal 
spaces  to  the  left,  as  before  directed.  Then  we 
would  have  but  four  ordinates,  and  would  num- 
ber them  as  follows:  1  at  3d,  2  at  6th,  3  at  9th 
and  4  at  12th.  At  1  we  would  have  a  pressure 
of  121  pounds;  at  2,  121  pounds  -*-  2  =  60.5;  at  3, 
121  pounds  -*•  3  =  40;  and  at  4,  121  pounds  •*•  4 
=  30. 

As  a  general  rule,  the  near  approximation  of 
the  expansion  curve  to  the  theoretical  or  hyper- 
bolic curve  may  be  taken  as  evidence  of  good 
conditions,  but  should  not  be  accepted  for  a  cer- 
tainty, unless  all  the  known  facts  and  conditions 
tend  in  the  same  direction. 

GEOMETRIC   METHOD    OF   FINDING  THE  HYPERBOLA. 

The  hyperbola  may  be  found  by  following 
the  directions  given  below,  in  connection  with 
Fig.  13.  A  is  the  atmospheric  line;  Zthe  zero 
line,  or  line  of  no  pressure;  B  the  line  of  boiler 
pressure,  and  C  the  clearance  line.  Locate  the 


STEAM     ENGINE. 


101 


first  point  in  the  hyperbola  at  the  point  of  release, 
X,  and  draw  the  vertical  line,  X E.  Then  draw 
diagonal  line  EH;  then,  from  X,  draw  horizontal 


FIG.  13. 

line  5  to  its  intersection  with  EH,  through  which 
draw  vertical  line,  F  O.  Now,  mark  off  points 
between  0  and  E,  as  1,  2,  3,  4— exact  spacing  is 
unnecessary — and  from  these  points  draw  di- 
agonal lines  to  H,  and  vertical  lines  down  to,  or 


^-^. <L'. ^S.r^_ne_ , 

FIG.   14. 

a  little  below,  the  actual  curve.  Now,  draw 
horizontal  lines  6,  7,  8  and  9  from  the  points  of 
intersection  in  the  line  F  O,  of  the  diagonal  lines 


102  INDICATING    THE 

H 4,  HZ,  H2  and  77  1,  respectively;  and  the 
points  where  these  lines  cross  the  vertical  lines, 
1,  2,  3  and  4,  in  connection  with  points  Jf  and  (9, 
are  the  points  throug-h  which  the  hyperbola 
should  be  drawn,  as  shown  b^  the  dotted  curve. 

ANOTHER  METHOD  OF  FINDING   THE  HYPERBOLA. 

Fig".  14,  shown  on  preceding"  pag-e,  illustrates 
another  method  of  finding-  the  hyperbola. 

Through  the  point  of  release  b  draw  any  line, 
as  a  B,  and  make  A  B  equal  to  a  b.  Then  draw 
any  other  line,  as  cD,  and  make  cd  equal  to  A  D  ; 
then  d  will  be  a  point  in  the  hyperbola  passing- 
from  b  to  A,  as  shown  by  the  dotted  curve.  By 
drawing-  a  number  of  lines  throug-h  A  and  fol- 
lowing- the  same  method,  we  can  find  as  many 
points  in  the  hyperbola. 


STKAM     ENGINE.  103 


CHAPTER  VII. 

AMSLER'S   POLAR    PLANIMETER,   WITH    DIRECTIONS 

FOR  USING  IT  ON  INDICATOR  DIAGRAMS. 
Fig-.  15  represents  the  No.  1  planimeter.  It 
is  the  simplest  form  of  the  instrument,  having 
but  one  wheel,  and  is  designed  to  measure 
areas  in  square  inches  and  decimals  of  a  square 
inch.  The  figures  on  the  roller  wheel  D  repre- 
sent units,  the  graduations  on  the  wheel  repre- 
sent tenths,  and  the  vernier  gives  the  hundredths. 


FIG.  15. 

Directions  for  Measuring  an  Indicator  Dia- 
gram with  a  No.  i  Planimeter. — Care  should  be 
taken  to  have  a  flat,  even,  unglazed  surface  for 
the  roller  wheel  to  travel  upon.  A  sheet  of  dull 
finished  cardboard  serves  the  purpose  very  well. 

Set  the  weight  in  position  on  the  pivot  end  of 
the  bar  P,  and  after  placing  the  instrument  and 
the  diagram  in  about  the  position  shown  in  the 
cut  (Fig.  16),  press  down  the  needle  point  so 
that  it  will  hold  its  place;  set  the  tracer  point  at 
any  given  point  in  the  outline  of  the  diagram,  as 
at  jF,  and  adjust  the  roller  wheel  to  zero.  Now 
follow  the  outline  of  the  diagram  carefully  with 
the  tracer  point,  moving  it  in  the  direction  indi- 
cated by  the  arrow,  or  that  of  the  hands  of  a 


104 


INDICATING    THE 


watch,  until  it  returns  to  the  point  of  beginning-. 
The  result  may  then  be  read  as  follows:  Suppose 
we  find  that  the  largest  figure  on  the  roller 
wheel  D  that  has  passed  by  zero  on  the  vernier 
E,  to  be  2  (units),  and  the  number  of  gradua- 
tions that  have  also  passed  zero  on  the  vernier  to 
be  4  (tenths),  and  the  number  of  the  graduation 
on  the  vernier  which  exactlv  coincides  with  a 


FIG.  16. 

graduation  on  the  wheel  to  be  8  (hundredths), 
then  we  have  2.48  square  inches  as  the  area  of 
the  diagram.  Divide  this  by  the  length  of  the 
diagram,  which  we  will  call  3  inches,  and  we 
have  .8266  inches  as  the  average  height  of  the 
diagram.  Multiply  this  by  the  scale  of  the  spring 
used  in  taking  the  diagram,  which  in  this  case  is 
40,  and  we  Have  33.06  pounds  as  the  mean  effect- 
ive pressure  per  square  inch  on  the  piston  of  the 
engine. 


STEAM    ENGINE.  105 

When  there  is  a  loop  in  the  diagram  (see  Fig-. 
10),  caused  by  the  steam  expanding  below  the 
back  pressure  line  when  the  engine  is  non-con- 
densing-, its  outline  should  be  traced  in  the  same 
way  as  directed  for  a  plain  diagram,  as  the  prin- 
ciple on  which  the  planimeter  works  is  such  that 
the  area  of  the  loop  will  be  subtracted  from  the 
main  part  of  the  diagram,  and  the  reading  of  the 
instrument  when  the  measurement  is  completed 
will  be  the  correct  net  area  sought. 

When  one  has  become  familiar  with  the  use 
of  the  planimeter  it  is  not  necessary  always  to 
set  the  wheels  at  zero,  as  required  in  the  forego- 
ing directions,  but  their  reading  as  they  stand 
just  before  beginning  to  trace  a  diagram  may 
be  noted  down,  and  this  quantity  subtracted 
from  the  reading  when  the  tracing  is  completed. 
The  difference  between  the  two  readings  is 
the  area  sought. 

The  use  of  Amsler's  Polar  planimeter  in  the 
measurement  of  indicator  diagrams  enables  one 
to  measure  ten  cards  with  it  in  the  time  which 
would  be  required  to  measure  one  card  by  any 
other  method,  and  it  insures  the  utmost  accu- 
racy in  the  work. 

The  planimeter  is  a  precise  and  delicate  in- 
strument, and  should  be  handled  and  kept  with 
great  care,  in  order  that  it  may  be  depended 
upon  to  give  correct  results.  After  using  it 
should  be  wiped  clean  with  a  piece  of  soft 
chamois  skin. 


(8) 


INDICATING 


THE 


REFRIGERATING    MACHINE 


PART  III. 
CONSTRUCTION  OF  INDICATORS. 


INTRODUCTION. 

MANUFACTURERS'    DESCRIPTION   OF  INDICATORS, 

PLANIMETERS,  REDUCING  WHEELS  AND  COF- 
FIN *S  AVERAGING  INSTRUMENT,  ETC. 

The  author  is  indebted  to  the  various  indi- 
cator manufacturers  for  the  following"  cuts  and 
descriptions  of  their  instruments.  The  indi- 
cators are  described  as  "Steam  Engine  Indi- 
cators," but  the  descriptions,  of  course,  apply 
equally  as  well  to  ammonia  compressor  indica- 
tors, the  only  difference  being-  that  for  com- 
pressor indicating-  most  manufacturers  make  an 
indicator  of  steel,  aluminum  or  composition 
metal,  to  resist  the  action  of  ammonia.  In  all 
other  particulars  the  indicators  are  the  same. 

I  recommend  that  the  reader  send  for  the 
catalogues  and  price  lists  of  these  instruments. 

The  catalog-ues  will  be  mailed  free  of  charg-e, 
and  many  of  them  are  quite  valuable  as  treatises 
on  indicator  practice. 


107 


108  CONSTRUCTION    OF    INDICATORS. 


CHAPTER  I. 

THE   CROSBY    INDICATOR. 

The  Crosby  Indicator  is  designed  and  con- 
structed to  meet  the  exacting-  requirements  of 
modern  engineering-.  During-  the  last  few  years, 
under  the  keen  search  and  exhaustive  tests 
of  eminent  engineers,  the  practice  in  this  de- 
partment of  science  has  underg-one  important 
chang-es,  tending-  to  establish  more  correct  meth- 
ods and  thereby  to  reach  more  accurate  results; 
especially  is  this  true  in  the  use  and  scope  of  the 
indicator,  so  that  the  work  done  with  this  instru- 
ment in  former  times  seems  coarse  and  crude 
when  compared  with  the  more  exact  attainment 
of  the  present. 

Educators  in  the  scientific  schools  of  both 
Europe  and  America  have  seen  the  importance 
of  more  exact  knowledg-e  and  instruction  in  the 
technical  sciences;  and  the  great  achievements 
of  recent  years  in  the  construction  of  building's, 
ships,  armaments  and  machines  attest  the  thor- 
oughness with  which  research  in  these  depart- 
ments has  been  prosecuted ;  in  none  has  there 
been  greater  progress  made  than  in  those  of 
mechanical  and  steam  engineering-. 

A  knowledg-e  of  these  facts  has  kept  the  manu- 
facturer of  the  steam  engine  and  ammonia  com- 
pressor indicator  on  the  alert.  Within  a  recent 
time,  the  Crosby  indicator  has,  without  any  great 
change  in  its  outward  appearance,  received  im- 
portant improvements.  Slight  changes  in  design, 
a  more  perfect  mechanical  construction  due  to  the 


CONSTRUCTION    OF    INDICATORS. 


109 


use  of  improved  and  specialized  machinery,  and  a 
careful  selection  of  metals  for  the  different  parts, 
have  all  contributed  to  this  favorable  result. 

The  movements  of  piston  and  pencil  point  are 
perfectly  parallel;  the  movement  of  the  pencil 
point  is  also  exactly  parallel  with  the  axis  of  the 
drum. 


FIG.  1. 


The  rating-  of  the  springs  by  the  newly  con- 
structed testing-  apparatus,  which  embodies  all 
the  valuable  aids  to  exactness  which  have  yet 
been  discovered,  is  nearer  perfection  than  could 
have  been  attained,  or  even  expected,  until  within 
a  very  recent  time. 

DKSCRIPTION    OF    THE    INDICATOR. 

The     illustration     shows     the     design    and 


110  CONSTRUCTION    OP^    INDICATORS. 

arrangement  of  the  parts  of  the  Crosby  steam 
engine  indicator. 

Part  4  is  the  cylinder  proper,  in  which  the 
movement  of  the  piston  takes  place.  It  is  made 
of  a  special  alloy,  exactly  suited  to  the  varying 
temperatures  to  which  it  is  subjected,  and  se- 
cures to  the  piston  the  same  freedom  of  move- 
ment with  high  pressure  steam  as  with  low ;  and 
as  its  bottom  end  is  free  and  out  of  contact  with 
all  other  parts,  its  longitudinal  expansion  or  con- 
traction is  unimpeded,  and  no  distortion  can  pos- 
sibly take  place. 

Between  parts  4  and  5  is  an  annular  chamber, 
which  serves  as  a  steam  jacket;  and  being-  open 
at  the  bottom,  can  hold  no  water,  but  will  always 
be  filled  with  steam  of  nearly  the  same  tempera- 
ture as  that  in  the  cylinder. 

The  piston  8  is  formed  from  a  solid  piece  of 
the  finest  tool  steel.  Its  shell  is  made  as  thin  as 
possible  consistent  with  proper  streng-th.  It  is 
hardened  to  prevent  any  reduction  of  its  area 
by  wearing-,  then  ground  and  lapped  to  fit  (to  the 
ten-thousandth  part  of  an  inch)  a  cylindrical 
gauge  of  standard  size.  Shallow  channels  in  its 
outer  surface  provide  a  steam  packing,  and  the 
moisture  and  oil  which  they  retain  act  as  lubri- 
cants, and  prevent  undue  leakage  by  the  piston. 

The  piston  rod  10  is  of  steel  and  is  made  hol- 
low for  lightness.  It  is  connected  with  the  piston 
by  a  screw  at  its  .lower  end.  When  these  parts 
are  connected,  be  sure  to  screw  the  rod  into  the 
slotted  socket  as  far  as  it  will  go;  that  is  until 
the  upper  edge  of  the  socket  is  set  firmly  against 
the  bottom  of  the  channel  formed  in  the  under 
side  of  the  shoulder  of  the  piston  rod.  This  is 


CONSTRUCTION    OF    INDICATORS.  Ill 

very  important,  as  it  insures  a  correct  alinement 
of  the  parts  and  a  free  movement  of  the  piston 
within  the  cylinder. 

The  swivel  head  12  is  screwed  into  the  upper 
end  of  the  piston  rod,  more  or  less  according-  to 
the  required  height  of  the  atmospheric  line  on 
the  diagram.  Its  head  is  pivoted  to  the  piston 
rod  link  of  the  pencil  mechanism. 

The  cap  2  rests  on  top  of  the  cylinder,  and 
holds  the  sleeve  and  all  connected  parts  in  place. 
The  smooth  portion  of  the  cap  which  fits  into  the 
top  of  the  cylinder  serves  as  a  guide  by  which  all 
the  moving  parts  are  adjusted  and  kept  in  correct 
alinement. 

The  sleeve  3  surrounds  the  upper  part  of  the 
cylinder  and  supports  the  pencil  mechanism. 
The  arm  X  is  an  integral  part  of  it.  The  handle 
for  adjusting  the  pencil  point  is  threaded  through 
the  arm,  and  in  contact  with  a  stop  screw  in  the 
plate  may  be  delicately  adjusted  to  the  surface 
of  the  paper  on  the  drum.  It  is  made  of  hard 
wood  in  two  sections ;  the  inner  one  may  be  used 
as  a  lock  nut  to  maintain  the  adjustment. 

The  pencil  mechanism  is  designed  to  afford 
sufficient  strength  and  steadiness  of  movement, 
with  the  utmost  lightness ;  thereby  eliminating, 
as  far  as  possible,  the  effect  of  momentum,  which 
is  especially  troublesome  in  high  speed  work. 
Its  fundamental  kinematic  principle  is  that  of 
the  pantograph.  The  fulcrum  of  the  mechanism 
as  a  whole,  the  point  attached  to  the  piston  rod 
and  the  pencil  point  are  always  in  a  straight  line. 
This  gives  to  the  pencil  point  a  movement  ex- 
actly parallel  with  that  of  the  piston.  The  pencil 
lever,  links  and  pins  are  all  made  of  hardened 


112  CONSTRUCTION    OF    INDICATORS. 

steel;  the  latter — slightly  tapering" — are  ground 
and  lapped  to  fit  accurately,  without  perceptible 
friction  or  lost  motion. 

Springs. — In  order  to  obtain  a  correct  dia- 
gram, the  height  of  the  pencil  of  the  indicator 
must  exactly  represent  in  pounds 
per  square  inch  the  pressure  on 
the  piston  of  the  steam  engine  at 
every  point  of  the  stroke ;  and  the 
velocity  of  the  surface  of  the 
drum  must  bear  at  every  instant 
a  constant  ratio  to  the  velocity 
of  the  piston.  These  two  essen- 
tial conditions  have  been  attained 
to  a  great  degree  of  exactness  in 
the  Crosby  indicator  by  a  very 
ingenious  construction  and  nice 
adaptation  of  both  its  piston  and 
drum  springs,  and  have  proved  satisfactory. 

The  piston  spring  is  of  unique  and  ingenious 
design,  being  made  of  a  single  piece  of  the  finest 
spring  steel  wire,  wound  from  the  middle  into  a 
double  coil,  the  spiral  ends  of  which  are  screwed 
into  a  brass  head  having  four  radial  wings  with 
spirally  drilled  holes  to  receive  and  hold  them 
securely  in  place.  Ad j  ustment  is  made  by  screw- 
ing them  into  the  head  more  or  less  until  exactly 
the  right  strength  of  spring  is  obtained,  when 
they  are  there  firmly  fixed.  This  method  of 
fastening  and  adjusting  removes  all  danger  of 
loosening  coils,  and  obviates  all  necessity  for 
grinding  the  wires. 

The  foot  of  the  spring — in  which  lightness  is 
of  great  importance,  it  being  the  part  subject  to 
the  greatest  movement — is  a  small  steel  bead, 


CONSTRUCTION    OF    INDICATORS.  113 

firmly  "staked"  on  to  the  wire.  This  takes  the 
place  of  the  heavy  brass  foot  used  in  other  indi- 
cators, and  reduces  the  inertia  and  momentum 
at  this  point  to  a  minimum,  whereby  a  great  im- 
provement is  effected.  This  bead  has  its  bearing 
in  the  center  of  the  piston,  and  in  connection  with 
the  lower  end  of  the  piston  rod  and  the  upper  end 
of  the  piston  screw  (both  of  which  are  concaved 
to  fit)  it  forms  a  ball-and-socket  joint  which 
allows  the  spring-  to  yield  to  pressure  from  any 
direction  without  causing-  the  piston  to  bind  in 
the  cylinder. 

The  drum  spring-  in  the  Crosby  indicator  is 
a  short  spiral. 

If  the  conditions  under  which  the  drum  spring- 
operates  be  considered,  it  will  readily  be  seen  that 
at  the  beginning-  of  the  stroke,  when  the  cord  hss 
all  the  resistance  of  the  drum  and  spring-  to  over- 
come, the  spring1  should  offer  less  resistance  than 
at  any  other  time ;  in  the  beginning-  of  the  stroke 
in  the  opposite  direction,  however,  when  the 
spring  has  to  overcome  the  inertia  and  friction  of 
the  drum,  its  energy  or  recoil  should  be  greatest. 

These  conditions  are  fully  met  in  the  Crosby 
indicator;  its  drum  spring  being  a  short  spiral, 
having  no  friction,  a  quick  recoil,  and  being  sci- 
entifically proportioned  to  the  work  it  has  to  do. 

The  drum  and  its  appurtenances,  except  the 
drum  spring,  are  similar  in  design  and  function 
to  like  parts  of  other  indicators,  and  need  not  be 
particularly  described.  All  the  moving  parts 
are  designed  to  secure  sufficient  strength  with 
the  utmost  lightness,  by  which  the  effect  of  in- 
ertia and  momentum  is  reduced  to  the  least  pos- 
sible amount. 


114  CONSTRUCTION    OF    INDICATORS. 

From  the  design  of  the  Crosby  indicator  as 
above  set  forth — the  conformation  and  purpose 
of  its  several  parts — it  will  be  seen  that  every 
opportunity  to  improve  the  instrument  has  been 
taken.  Add  to  this  the  fact  that  only  the  most 
skillful  workmen  of  long-  training-  in  the  art  are 
employed,  and  that  every  part  is  made  to  a  stand- 
ard size  by  modern  specialized  machinery,  with 
tools  perfectly  adapted  to  their  work,  and  it  will 
be  admitted  that  the  proper  means  have  been 
taken  to  produce  a  first-class  indicator.  We  be- 
lieve this  object  has  been  accomplished. 

All  Crosby  indicators  are  chang-eable  from 
rig-fat  hand  to  left  hand  instruments  if  occasion 
requires. 

The  Crosby  indicator  is  ordinarily  made  with 
a  drum  one  and  one-half  inches  in  diameter,  this 
being-  the  correct  size  for  hig-h  speed  work,  and 
answering-  equally  well  for  low  speeds.  If,  how- 
ever, the  indicator  is  to  be  used  only  for  low 
speeds,  and  a  long-er  diagram  is  preferred,  it  can 
be  furnished  with  a  2-inch  drum. 

The  Crosby  indicator  in  a  special  design  is 
made  to  indicate  extremely  hig-h  pressures.  In- 
struments of  this  desig-n  have  been  used  with 
perfect  success  in  the  testing-  of  ordnance  and 
for  other  explosive  effects. 

When  desired  the  Crosby  indicator  is  made 
of  steel,  to  resist  the  action  of  ammonia. 

A  detent  attachment  is  furnished  with  the 
instrument  when  required. 

Every  part  of  the  Crosby  indicator  is  per- 
fectly adapted  to  its  particular  function,  also  to 
its  relation  to  all  the  other  parts,  in  size,  pro- 
portion and  material.  Its  small  size  and  lig-ht 


CONSTRUCTION    OF    INDICATORS.  115 

weight  serve  to  protect  it  from  accident,  and  so 
contribute  to  its  durability  and  to  the  facility 
with  which  it  can  be  handled. 

Full  particulars  for  the  proper  care  and  hand- 
ling- of  the  Crosby  indicator  accompany  each  in- 
strument. They  are  manufactured  only  by  the 
Crosby  Steam  Gage  and  Valve  Co.,  Boston,  Mass. 


116 


CONSTRUCTION    OF    INDICATORS. 


CHAPTER  II. 

THE  BACHELDER  ADJUSTABLE  SPRING  INDICATOR. 

Since  the  introduction  of  the  Bachelder  indi- 
cator to  the  pub- 
lic some  years  ago 
it  has  been  mate- 
rially improved, 
both  in  design  and 
detail  of  construc- 
tion. 

The  flat  spring- 
is  no  longer  an  ex- 
periment, but  an 
established  suc- 
cess as  to  accu- 
racy and  durabil- 


FIG. 


ity.  The  downward  motion  of  the  spring-  being 
the  same  as  the  upward,  a  correct  record  is 
shown  of  a  condensing  or  low  pressure  cylinder 
of  a  compound  engine. 

DESCRIPTION    OF    THE   INDICATOR. 

The  special  features  of  this  instrument  con- 
sist of  the  T  shaped  hollow  case,  and  adjustable 
flat  spring.  The  cylinder,  being  separate  from 
the  case  proper,  is  screwed  to  the  lower  end, 
where  it  is  held  by  a  small  set  screw.  By  turn- 
ing this  screw  one-half  of  a  turn  the-cylinder  can 
be  unscrewed;  then  to  remove  the  piston,  take 
out  the  screw  at  the  piston  end  of  the  spring, 
and  at  the  connection  with  pencil  lever.  These 
are  the  only  parts  necessary  to  remove  for 
cleaning.  The  flat  steel  spring  works  in  the 


CONSTRUCTION    OF   INDICATORS.  117 

horizontal  body  of  the  case,  one  end  being- 
rig-idly  secured  by  means  of  a  taper  steel  screw, 
and  the  other  attached  to  the  connecting-  rod  be- 
tween the  piston  and  pencil  lever.  The  chang-e 
of  spring- is  made  by  removing-  the  screw  that 
connects  it  to  the  piston  rod,  and  the  one  which 
holds  it  in  the  case.  The  rang-e  of  the  hig-h 
pressure  spring-  is  so  great  that  a  chang-e  is  only 
necessary  when  using-  on  a  compound  or  triple 


FiG.  4. 

expansion  eng-ine.  Connection  is  made  to  the 
piston  with  a  ball  and  socket  joint.  Access  can 
be  had  to  the  piston  for  oiling-  or  removing-,  by 
unscrewing-  knurled  cap  on  face  of  instrument. 

A  split  bushing-  in  the  case  is  provided  with  a 
longitudinal  recess  for  the  reception  of  the 
spring-.  In  the  upper  side  of  the  bushing-  a  hard- 
ened steel  pin  is  inserted.  The  lower  side  of  the 
case  has  a  longitudinal  slot,  through  which  a  set 
screw  passes  and  throug-h  the  lower  side  of  the 


118  CONSTRUCTION    OF    INDICATORS. 

bushing,  directly  opposite  the  steel  pin,  so  that 
when  the  screw  is  tightened,  the  spring  is  held 
rigidly  between  it  and  the  steel  pin.  To  change 
from  one  scale  to  another,  loosen  the  set  screw 
and  slide  the  bushing  along  until  the  mark  on 
projecting  block  is  opposite  the  scale  required, 
then  tighten  the  screw.  The  scales  are  marked 
on  the  face  of  the  case,  the  upper  one  being  for 
high  pressure,  and  the  other  for  low  pressure. 
The  parallel  motion  is  of  the  latest  improved 
design,  is  entirely  accurate  and  free  from  lost 
motion  or  friction.  The  height  of  atmospheric 
line  is  adjustable  by  means  of  a  swivel  in  connect- 
ing rod  near  the  pencil  lever.  With  this  brief 
description  and  a  reference  to  the  accompanying 
cuts,  the  general  principle  will  be  readily  under- 
stood. 

Each  indicator  is  furnished  with  two  flat 
springs,  which  are  equivalent  to  eleven  spiral 
springs. 

The  low  pressure  springs  have  the  scales  of 
10,  15,  20  and  25.  The  high  pressure  springs 
have  the  scales  of  30,  40,  50,  60,  70,  80  and  90,  so 
that  cards  of  proper  height  can  be  taken  at  any 
pressure  up  to  175  pounds.  A  special  instru- 
ment for  ammonia  use,  or  for  higher  pressures 
than  the  above  is  furnished  when  required. 

The  Bachelder  indicator  is  manufactured 
only  by  John  S.  Bushnell,  successor  to  Thomp- 
son &  Bushnell,-  120  and  122  Liberty  street, 
New  York  City. 


CONSTRUCTION   OF    INDICATORS.  119 


CHAPTER  III. 

IMPROVED  ROBERTSON-THOMPSON  INDICATOR. 

The  improved  Robertson-Thompson  indica- 
tor, which  has  just  been  placed  on  the  market,  is 
unusually  heavy,  but  as  a  result  of  most  careful 
experiment  this  weight  is  so  perfectly  distribu- 
ted that  the  best  results  may  be  attained  at 
speeds  far  in  excess  of  any  met  with  in  actual 
practice.  One  of  the  most  serious  errors  in  or- 
dinary indicator  work  is  caused  by  flexure  of 
the  arm  which  carries  the  drum,  particularly 
when  the  cord  is  carried  above  or  below  the  in- 
strument. In  this  manner  an  error  of  10  per 
cent  is  easily  possible,  particularly  if  the  instru- 
ment is  being-  used  with  a  high  pressure  spring. 
For  instance,  with  an  80  spring-  it  would  re- 
quire a  movement  of  but  one-eightieth  of  an  inch 
to  show  an  error  of  one  pound.  In  many  cases 
weakness  at  this  point  will  account  for  the  curi- 
ous features  often  noticed  at  the  junction  of  the 
admission  and  steam  lines  on  the  diagram.  The 
drum  carrying  arm  of  the  improved  Robertson- 
Thompson  indicator  is  so  stiff  that  no  error  from 
this  cause  is  possible. 

DESCRIPTION  OF  THE  INDICATOR. 

The  cylinder  is  steam  jacketed,  and  by  its 
construction  the  possibility  of  the  piston  being 
cramped  as  a  result  of  external  strains  is  pre- 
cluded. The  area  of  this  cylinder  is  exactly 
one-half  inch,  and  each  spring  is  suitable  for 
twice  the  pressure  stamped  on  it;  for  instance, 
a  60  spring  may  be  used  for  a  pressure  of  120 


120 


CONSTRUCTION    OF    INDICATORS. 


pounds  or  less.  The  coupling"  is  reamed  to  %  -inch 
area,  and  with  each  instrument  an  extra  ^-inch 
piston  is  furnished.  With  this  piston  each  spring 
may  be  used  for  pressures  four  times  as  great  as 
the  number  stampthereon,  so  that  with  a60spring- 
240  pounds  may  be  safely  indicated.  This  extra 
piston  is  of  special  value  for  hydraulic  and  g-as  en- 
g-ine  work.  The  pistons  are  made  of  steel,  but 
phosphor  bronze  will  be  substituted  if  preferred. 


FIG.  5. 

The  piston  spring's  are  standardized  by  the  most 
approved  testing-  apparatus,  in  connection  with 
a  mercury  column.  To  guarantee  against  press- 
ure above  the  piston,  a  large  relief  opening  has 
been  provided,  the  outlet  being-  a  neat  swivel 
elbow,  by  means  of  which  the  "blow"  may  be 
discharged  in  any  direction,  at  the  will  of  the 
operator.  Each  instrument  is  provided  with  a 
detent  or  stop  motion. 

In  Fig.  6  a  new  device  is  shown  for  adjusting- 


CONSTRUCTION    OF    INDICATORS. 


121 


the  tension  of  the  drum  spring1. 
By  rotating-  the  knurled  head 
S,  to  the  rig-lit  the  spring-  may 
be  tightened  as  much  as  de- 
sired, and  securely  held  by 
pawl  P;  the  ratchet  wheel  N 
is  securely  attached  to  the  shaft 
by  means  of  a  left  hand  thread. 
FIG.  6.  Thus  the  tendency  of  the  drum 

spring-  is  to  tighten  the  ratchet  nut  more  firmly. 
By  pressing-  the  thumb  into  the  recess  in  the 
spring-  winder  S,  the  pawl  is  released,  when  the 
tension  maybe  diminished  to  any  desired  amount. 
This  ratchet  wheel  has  sixteen  teeth,  which  pro- 
vide for  the  adjustment  of  the  spring  to  a  nicety. 
Drum  springs  are  of  the  clock  type,  but  spiral 
form  will  be  furnished  if  preferred.  Cone  bear- 
ings are  provided  to  take  up  all  wear  of  the  drum 
spindle.  The  parallel  movement  is  made  of  tool 
steel,  highly  polished  and  richly  blued.  All 
bearings  are  wide  and  perfectly  fitted. 

In  Fig.  7  the  pencil  mechanism  is  shown  in 
three  positions,  which  will  give  a  perfect  idea 
of  the  manner  in  which  an  absolutely  correct 
straight  line  is  obtained.  This  movement  forms 
a  perfect  pantograph, 
so  that  the  pencil  move- 
ment is  exactly  propor- 
tional to  that  of  the  pis- 
ton, theratiobeing5tol. 
All  moving  parts  are 
worked  down  to  the  lightest  weight  consistent 
with  durability.  For  comparison  it  may  be  stated 
that  the  drum  weight  is  but  one  and  one-fourth 
ounces,  and  the  pencil  lever  twenty-five  grains. 

(9) 


FIG. 


122  CONSTRUCTION    OF    INDICATORS. 

By  special  order,  the  instrument  will  be  fitted 
with  the  improved  Victor  reducing-  wheel,  which 
comprises  a  patent  cord  feeding-  device.  The 
manufacturers  are  James  L.  Robertson  &  Sons, 
No.  204  Fulton  street,  New  York  city. 


CONSTRUCTION   OF   INDICATORS.  123 


CHAPTER  IV. 

THE   BUFFALO    INDICATOR. 

The  Buffalo  indicator  is  of  standard  size,  and 
well  made  throughout.  It  is  handsome  in  design 
and  finish,  all  working-  parts  being-  accurately 
fitted  and  carefully  tested.  The  working-  parts 
are  few,  and  of  such  light  weight  that  a  quick  re- 
sponse to  the  steam  pressure  is  always  insured. 
A  new  style  double  coil  spring  of  high  tension 
is  used,  which  insures  correct  diagrams.  The 
piston  is  ^2-inch  area,  provided  with 
water  grooves.  The  piston  rod  is 
made  of  rVmch  steel, 
hollow  at  the  upper  end, 
threaded  to  receive  a 
swivel  head  (which  per- 
mits of  the  adjustment  of 
the  pencil  to  suit  weak  or 
strong  vacuum  springs), 
and  turned  smaller  at  the 
lower,  to  reduce  its  weight. 

The  parallel  motion  is  sms^*»  pIG<  8. 
secured  by  a  link  attached  to  and  governing  the 
pencil  lever  direct.  The  screws  of  this  link  are 
made  free  from  any  appreciable  loss  motion,  and 
will  remain  so  indefinitely.  It  is  made  of  "tool 
steel,"  and  will  trace  a  correct  vertical  line  within 
its  limit  of  three  inches.  The  arm,  link  and  up- 
rights are  made  of  r\  X  ^-inch  steel,  the  uprights 
being  held  together  by  small  bars  /^-inch  diam- 
eter, one-half  inch  long,  the  ends  of  which  are 
turned  smaller,  and  threaded  to  receive  the  ^-i 


124 


CONSTRUCTION    OF    INDICATORS. 


hex  nut,  which  fastens  the  uprights  against  the 
shoulder.  The  lower  bar  is  centered  at  the 
proper  angle  to  fit  the  pivot  screws,  and  permit 
of  very  fine  adjustment.  Bearings  of  the  link  are 
one-fourth  inch  long.  The  entire  movement  is 
carefully  blued.  The  movement  of  the  pencil 
coincides  with  that  of  the  piston  at  all  times,  and 
is  acknowledged  to  be  the  most  accurate  made. 
The  rosewood  handle  that  swings  the  pencil 


FIG.  9. 

movement  can  be  screwed  in  or  out  against  the 
stop  post  so  as  to  get  the  required  pressure  of 
lead  or  wire  upon  the  card. 

For  ordinary  use,  drums  1.75  inches  diam- 
eter, three  and  one-half  inches  high — two  inches 
when  specified — are  furnished.  They  are  made 
from  special  drawn  telescope  tubing,  turned  as 
thin  as  is  consistent  with  ordinary  usage,  and 
supported  at  the  top  by  a  bearing  one-half  inch 
long.  The  barrel,  which  carries  the  drum,  it  will 
be  noticed  by  reference  to  the  cut,  is  very  light, 


CONSTRUCTION   OF   INDICATORS.  125 

and  is  provided  with  adjustable  cone  bearings. 
The  drum  spring-  is  a  flat  coil  of  the  clock  pattern, 
and  can  be  adjusted  for  any  speed  met  in  prac- 
tice, by  unscrewing-  the  thumb  screw,  turning-  to 
the  quarter,  then  tighten  as  shown.  The  arm 
which  carries  the  g-uide  pulleys  can  be  adjusted 
to  allow  the  cord  to  run  in  any  direction  without 
the  aid  of  carrying-  pulleys.  The  drum  cord 
will  not  climb  from  one  coil  to  another,  and  can 
be  adjusted  to  any  angle  by  means  of  the  g-uide 
pulleys. 

The  indicator  is  made  almost  entirely  of 
brass,  highly  polished  and  nickeled;  but  for  am- 
monia a  special  composition  is  used.  Each  in- 
dicator is  sent  out  in  a  polished  mahogany  box, 
fitted  with  a  metal  plate,  to  which  the  indicator 
is  attached  by  means  of  the  coupling  and  plug. 


126  CONSTRUCTION    OF   INDICATORS. 


CHAPTER  V. 

AMERICAN  THOMPSON  INDICATOR. 

The  American  Thompson  improved  indi- 
cator was  patented  by  J.  W.  Thompson,  August 
31,  1875,  and  July  12,  1881. 

The  radical  improvements,  as  made  in  the  old 
style  Thompson  indicator,  consist  of  lightening 
the  moving  parts,  substituting  steel  screws  in 
place  of  taper  pins,  using  a  very  light  steel  link 
instead  of  a  large  brass  one,  reducing  the  weight 
of  the  pencil  lever,  also  weight  of  squares  on 
trunk  of  piston  and  lock  nut  on  end  of  spindle, 
and  increasing  the  bearing  on  connection  of  par- 
allel motion.  By  shortening  the  length  and  re- 
ducing the  actual  weight  of  the  paper  cylinder 
just  one-half,  and  by  shortening  the  bearing  on 
spindle,  also  lowering  the  spring  casing  to  a 
nearer  plane  to  that  in  which  the  cord  runs,  we 
have  reduced  the  momentum  of  the  paper  cylin- 
der to  a  very  small  amount.  All  of  these  im- 
provements have  lessened  the  amount  of  friction, 
which  was  heretofore  very  small,  but  is  now 
reduced  to  a  minimum. 

The  parallel  movement  of  pencil  is  secured 
by  a  link  attached  to  and  governing  the  lever 
direct.  The  pivots  of  this  link  are  made  free 
from  any  appreciable  lost  motion,  and  will  remain 
so  indefinitely;  but  if  any  such  lost  motion  should 
exist,  it  will  affect  the  integrity  of  the  parallel 
movement  only  to  an  extent  equal  to  it.  The 
parallel  movement  will  be  affected  only  by  the 
play  in  the  pivots  of  the  link,  and  not  in  any  de- 
gree or  manner  by  the  play  of  any  other  parts. 


CONSTRUCTION    OF    INDICATORS.  127 

The  force  required  to  guide  the  lever  in  its 
parallel  movement  is  received  on  the  pivots  of 
the  link  alone,  where  the  friction  it  causes  is 
practically  inappreciable. 

With  the  slot  and  roller  device  this  guiding 
force  is  received  on  several  rapidly  moving-  sur- 
faces, multiplied  in  amount  by  leverage.  The 
same  is  true  to  a  considerable  extent  of  the  plan 
of  attaching  the  link  to  the  connecting  rod. 


FIG.  10.  .     _v.    . 

The  Paper  Cylinder  Movement. — It  is  so  con- 
structed that  the  tension  of  the  coiled  drum 
spring  within  the  paper  cylinder  can;be  increased 
or  decreased,  for  different  speeds  of  engines. 
As  little  or  as  much  of  the  spring  can  be  taken  up 
or  let  out  as  desired,  thereby  providing  for  fine 
adjustments. 

For  high  speeds  the  instrument  will  give  ac- 
curate results  for  all  practical  purposes,  without 


128 


CONSTRUCTION    OF    INDICATORS. 


any  special  adjustments  further  than  to  give  suf- 
ficient tension  to  keep  the  cord  taut  at  all  points. 
When  exceptionally  accurate  work  is  desired, 
the  length  of  the  diagram  may  be  carefully 
measured,  and  compared  with  the  length  of  a 
line  traced  on  the  paper  when  the  engine  is  work- 
ing slowly.  If  the  diagram  is  found  to  differ  in 

length  from  this  line, 
vary  the  tension  of 
the  spring  till  they 
agree.  The  paper 
cylinder,  or  "drum," 
is  now  made  with 
covered  top. 

The  leading  pul- 
ley for  paper  cylin- 
der, the  latest  im- 
provement in  the 
American  Thomp- 
son improved  indica- 
tor, was  patented 
FlG-  n-  June  26,  1883,  and 

consists  (see  Fig.  10)  of  a  wheel  which  leads 
the  cord  through  the  hole,  in  contact  with  the 
scored  wheel,  over  which  the  cord  can  be  run  to 
any  possible  angle,  to  connect  with  the  motion 
wherever  it  may  be,  or  of  whatever  kind. 

The  pulley  works  in  a  sleeve  which  rotates  in 
the  stand  according  to  the  adjustments  required, 
and  which  is  held  in  its  position,  where  adjusted 
by  the  thumb  screw,  which  acts  as  a  binding 
screw  working  in  the  groove  on  the  sleeve.  By 
this  it  is  held  in  any  position  that  may  be  chosen, 
and  yet  is  free  to  revolve  the  moment  the  bind- 
ing screw  is  loosened,  without  any  possibility  of 


CONSTRUCTION    OF    INDICATORS.  129 

interfering-  with  the  motion  by  means  of  scarring 
the  sleeve  or  disturbing-  the  particles  of  metal  on 
surface.  It  also  gives  all  the  desired  freedom  of 
motion  and  facility  of  adjustment. 

By  means  of  the  set  screw,  the  stand  which 
carries  the  wheel  can  be  adjusted  to  run  the  cord 
to  any  possible  angle  within  a  rang-e  of  360°. 

In  the  double-pulley  arrang-ement,  as  used  in 
other  indicators,  the  range  of  adjustment  is 
limited,  and  in  some  cases  the  cord  cannot  be 
made  to  run  in  a  number  of  certain  directions, 
except  in  a  grating1,  roug-h  and  uneven  manner. 

In  this  improved  swivel  pulley  the  use  of 
carrying  pulleys  is  done  away  with,  and  from  the 
fact  that,  no  matter  what  the  angle  of  deflection 
may  be,  or  what  direction  it  may  be  necessary  to 
take  the  cord,  it  will  work  smoothly;  for  the 
pulley  face  and  the  face  of  the  groove  on  the 
paper  cylinder  are  always  in  the  proper  position, 
one  with  the  other,  to  take  the  cord  to  the  mo- 
tion, wherever  that  may  be  arranged. 

In  high  speed,  short  stroke  electric  light  en- 
gines great  range  of  adjustment  is  very  impor- 
tant; for  considerable  trouble  is  experienced 
sometimes  upon  engines  running  350  and  360 
revolutions  per  minute,  in  arranging  the  cords  so 
as  to  use  independent  arcs,  and  in  making  such 
connections  with  reference  to  right  lines,  that  no 
distortion  of  diagrams  should  be  given. 

It  is  provided  with  a  "stop motion  "  (see  Fig. 
10),  which  is  so  arranged  that  the  horn  handle 
screw  can  be  screwed  up  against  the  post  or  stop 
placed  midway  between  paper  cylinder  and  steam 
cylinder  so  as  to  regulate  the  pressure  of  pencil 
lead  upon  the  paper. 


130  CONSTRUCTION    OF    INDICATORS. 

The  best  and  finest  quality  of  steel  wire  is 
used  in  making"  our  spring's;  and  they  are  all 
wound  on  a  mandrel  and  tempered  in  the  most 
careful  manner  by  the  oldest  and  most  experi- 
enced workmen  in  the  business. 

All  spring's  are  wound  on  mandrels  from 
four  to  four  and  one-half  threads  to  the  inch,  and 
thereby  give  more  wire  to  each  spring-,  and  a 
consequent  less  strain,  than  if  wound,  as  in 
spring's  of  other  indicators,  on  mandrels  two  to 
three  threads  to  the  inch. 

Whatever  grinding-  is  done  to  lig-hten  a  spring- 
amounts  to  very  little;  in  fact,  at  the  most  it  is 


FIG.  12. 

never  ground  to  cause  more  than  one  to  three 
pounds  difference  in  100  pounds;  and,  when  the 
sensitiveness  of  the  spring  is  considered,  very 
little  grinding  will  produce  this  result. 

All  springs  made  are  scaled,  providing  for 
vacuum;  and  the  capacity  of  any  spring  can  be  as- 
certained by  the  following  general  rule:  Multiply 
scale  of  spring  by  2/^,  and  subtract  15,  and  the 
result  will  be  the  limit  of  pounds  steam  pressure 
to  which  spring  should  be  subjected.  Example: 
40-pound  spring  X  2%  =  100  —  15  ==  85  pounds 
pressure,  capacity  of  a  40-pound  spring. 

To  adapt  the  American  Thompson  improved 
indicator  to  all  pressures,  springs  are  made  to 
any  desired  scale.  The  following  are  the  most 
generally  used  :  8,  10,  12,  16,  20,  24,  30,  32,  40,  48, 


CONSTRUCTION    OF    INDICATORS.  131 

50,  56,  60, 64, 72, 80, 100.  For  pressures  from  65  to 
85  pounds,  a  40-pound  spring-  is  best  adapted; 
for,  as  40  pounds  pressure  on  a  40-pound  spring- 
will  raise  pencil  one  inch,  80  pounds  pressure  on 
the  same  spring-  will  raise  pencil  about  two 
inches,  which  is  the  usual  height  of  a  diagram. 

All  the  spring's  are  scaled  providing-  for 
vacuum,  but  close  experiments  have  shown 
that,  from  the  fact  that  spring's  compress  and 
elong-ate  in  unlike  proportions,  the  regular  press- 
ure springs  vary  about  one  pound  in  fifteen,  or 
about  6^i  per  cent.  A  special  vacuum  spring  is 
made  with  regular  thread,  scaled  for  vacuum  only. 
..  The  detent  motion,  as  applied  to  the  American 
Thompson  indicator,  consists  of  a  pawl  mounted 
on  a  stud,  combined  with  a  spring 'and  ratchet, 
by  the  use  of  which  the  paper  cylinder  can  be 
stopped  and  a  change  of  cards  made  without 
unhooking  or  disconnecting  the  indicator  cord. 

By  moving  the  pawl  so  as  to  catch  in  the 
teeth  of  the  ratchet  on  base  of  paper  cylinder, 
the  latter  is  held  stationary  as  the  engine  com- 
pletes its  stroke.  The  cord,  being  entirely  free, 
runs  loosely  with  the  motion  of  the  engine,  but 
the  paper  cylinder  being  stationary,  the  cards 
can  be  changed  without  the  least  disturbance  of 
adjustments.  By  throwing  the  pawl  out  of  the 
ratchet  the  paper  cylinder  is  released,  and  im- 
mediately resumes  its  stroke  with  the  engine, 
but  care  must  be  taken  not  to  allow  the  paper 
cylinder,  by  force  of  its  spring,  to  return  to  the 
stop  with  a  thump;  this  can  easily  be  done  by 
simply  holding  the  cord  slightly  with  the  thumb 
and  finger  until  the  beginning  of  the  next  stroke. 
This  device  obviates  the  change  of  adjustments, 


132 


CONSTRUCTION    OF    INDICATORS. 


and  is  particularly  valuable  to  amateurs  and 
others  not  familiar  with  the  use  of  the  indicator. 
It  is  also  valuable  to  users  of  the  indicator  on 
very  quick  running-  electric  lig-ht  engines,  and  in 
all  cases  where  the  circumstances  are  such  that 
the  disconnection  of  the  connecting-  cord  must 
cause  the  operator  considerable  trouble  and  the 
loss  of  valuable  time. 

All  American  Thompson  improved  indicators 

are  provided  with  a 
piston  .798-inch  di- 
ameter =  %-mch 
area,  which,  with  the 
100-pound  spring1, 
provides  for  indicat- 
ing pressure  up  to 
250  pounds. 

When  pressure 
above  that  is  to  be 
indicated,  an  extra 
pistonis  furnishedof 
.564-inch  diameter^ 
^-inch  area,  which, 
when  substituted  for 
the  >^-inch  area  pis- 
ton, doubles  the  capacity  of  each  spring-,  thereby 
adapting-  the  indicator  for  indicating-  pressures 
up  to  500  pounds. 

From  the  above  it  will  be  seen  that  when  an 
indicator  is  furnished  with  the  regular  ^2 -inch 
area  piston,  and  an  extra  %'-inch  area  piston  in 
addition,  the  instrument  can  be  used  to  indicate 
all  pressures  from  0  to  500  pounds. 

This  indicator  is  constructed  of  steel  for 
ammonia  compressor  work. 


FIG.  13. 


CONSTRUCTION    OF    INDICATORS.  133 


CHAPTER  VI. 

THE    TABOR     INDICATOR. 

The  special  peculiarity  of  the  Tabor  indicator 
lies  in  the  means  employed  to  communicate  a 
straig-ht  line  movement  to  the  pencil.  This  and 
other  features  of  the  instrument  are  shown  in 
the  appended  cuts,  and  these  are  so  clear  that 
little  explanation  is  needed.  A  stationary  plate 
containing*  a  curved  slot  is  firmly  secured  in  an 
upright  position  to  the  cover  of  the  steam  cylin- 
der. This  slot  serves  as  a  guide  and  controls 
the  motion  of  the  pencil  bar.  The  side  of  the 
pencil  bar  carries  a  roller  which  turns  on  a  pin, 
and  this  fitted  so  as  to  roll  freely  from  end  to  end 
of  the  slot  with  little  lost  motion.  The  cur  ve  of  the 
the  slot  is  so  adjusted  and  the  pin  attached  to 
such  a  point,  that  the  end  of  the  pencil  bar,  which 
carries  the  pencil,  moves  up  and  down  in  a 
straight  line,  when  the  roller  is  removed  from 
one  end  of  the  slot  to  the  other.  The  curve  of 
the  slot  just  compensates  the  tendency  of  the 
pencil  point  to  move  in  a  circular  arc,  and  a 
straight-line  motion  results. 

The  pencil  mechanism  is  carried  by  the  cover 
of  the  outside  cylinder.  The  cover  proper  is  sta- 
tionary, but  a  nicely  fitted  swivel  plate,  which  ex- 
tends over  nearly  the  whole  of  the  cover,  is  provid- 
ed, and  to  this  plate  the  direct  attachment  of  the 
pencilmechanismismade.  By  means  of  the  swivel 
plate,  the  pencil  mechanism  may  be  turned  so  as 
to  bring*  the  pencil  into  contact  with  the  paper 
drum,  as  is  done  in  the  act  of  taking  a  diagram. 


134 


CONSTRUCTION    OF    INDICATORS. 


The  pencil  mechanism  is  attached  to  the 
swivel  by  means  of  the  vertical  plate  containing 
the  slot,  which  has  been  referred  to,  and  a  small 
standard  placed  on  the  opposite  side  of  the  swivel 
for  connecting-  the  back  link.  The  slotted  plate 
is  backed  by  another  plate  of  similar  size,  which 
serves  to  receive  the  pressure  brought  to  bear 
on  the  pencil  bar  when  taking-  diagrams,  and  to 
keep  the  pencil  bar  in  place.  The  pencil  mechan- 
ism consists  of  three  pieces:  The  pencil  bar,  the 


FIG.  14. 


back  link  and  the  piston  rod  link.  The  two  links 
are  parallel  with  each  other  in  every  position  they 
may  assume.  The  lower  pivots  of  these  links 
and  the  pencil  point  are  always  in  the  same 
straig-ht  line.  If  an  imaginary  link  be  supposed 
to  connect  the  two  in  such  a  manner  as  to  be  par- 
allel with  the  pencil  bar,  the  combination  would 
form  an  exact  pantograph.  The  slot  and  roller 
serve  the  purpose  of  this  imaginary  link. 

The  connection  between  the  piston  and  the 


OF 


CONSTRUCTION    OF    INDICATORS. 


135 


pencil  mechanism  is  made  by  means  of  a  steel 
piston  rod.  At  the  upper  end,  where  it  passes 
through  the  cover,  it  is  hollow  and  has  an  outside 
diameter  measuring-  three-sixteenths  of  an  inch. 
At  the  lower  end  it  is  solid  and  its  diameter  is 
reduced.  It  connects  with  the  piston  througti  a 
ball  and  socket  joint.  The  socket  forms  an  in- 
dependent piece,  which  fits  into  a  square  hole  in 
the  center  of  the  pis- 
ton, and  is  fastened 
by  means  of  a  central 
stem  provided  with  a 
screw,  which  passes 
through  the  hole  and 
receives  a  nut  ap- 
plied from  the  under 
side.  The  nut  has 
a  flat  sided  head,  so 
as  to  be  readily  oper- 
ated by  the  fingers. 
A  number  of  shallow 
grooves  are  cut  upon 
the  outside  of  the  piston,  to  serve  as  a  so  called 
water  packing1. 

Purchasers  of  indicators  have  many  import- 
ant points  to  consider  carefully  before  buying-  an 
instrument  of  such  precision  as  an  indicator 
should  be,  to  be  reliable.  One  of  the  most  im- 
portant features  of  an  indicator  is  the  parallel 
motion.  It  is  one  that  has  engrossed  the  atten- 
tion of  leading-  engineers  and  inventors  for  the 
past  quarter  of  a  century  •:  that  the  correctness 
of  the  parallel  motion  of  the  Tabor  indicator  is 
such  that  at  all  times  and  at  every  point  on  a 
diagram  within  the  reacH  of  the  pencil  point,  the 


FIG.  15. 


136  CONSTRUCTION    OF    INDICATORS. 

extreme  end  of  the  pencil  bar  will  record  a  ver- 
tical travel  or  movement  of  just  five  times  that 
of  the  indicator  piston. 

The  spring's  used  in  the  Tabor  indicator  are 
of  the  duplex  type,  being1  made  of  two  spiral 
coils  of  wire  with  fitting's,  as  shown  in  the  cut. 
The  springs  are  so  mounted  that  the  points  of 
connection  of  the  two  coils  lie  on  opposite  sides 
of  the  fitting.  This  arrangement  equalizes  the 
side  strain  on  the  spring,  and  keeps  the  piston 
central  in  the  cylinder,  avoiding  the  excessive 
friction  caused  by  a  single  coil  spring  forcing 
the  piston  against  the  side  of  the  cylinder.  The 
thread  by  which  the  spring  is  attached  is  cut  on 
the  inside  of  the  fitting,  and  suitable  threaded 
projections  on  the  under  side  of  the  cover  and 
on  the  upper  side  of  the  piston,  respectively,  are 
provided  for  its  attachment. 

The  springs  are  adjusted  under  steam  press- 
ure, and  are,  consequently,  correct  only  when 
used  for  steam  engines.  If  required  for  water  or 
other  purposes,  either  special  springs  should  be 
obtained  that  are  adjusted  with  reference  to  the 
required  use,  or  the  springs  should  be  tested  at 
the  time,  and  the  actual  scale  of  the  spring  deter- 
mined. It  should  be  borne  in  mind  that  a  spring 
becomes  impaired  by  continued  use,  and  its  scale 
changes.  For  important  work,  therefore,  the 
accuracy  of  the  spring  should  always  be  tested 
by  comparison  on  the  spot  with  a  reliable  steam 
gauge,  employing,  as  nearly  as  possible,  the  con- 
ditions under  which  the  instrument  was  used. 
For  steam  work,  they  may  be  tested  by  attach- 
ing to  the  main  steam  pipe,  for  this  purpose,  a 
half-inch  pipe  fitted  with  a  globe  valve,  a  tee  for 


CONSTRUCTION    OF    INDICATORS. 


137 


the  attachment  of  the  indicator,  another  tee  for 
the  steam  gauge,  and  finally  a  small  drip  valve. 
By  keeping-  the  drip  valve  slightly  open  and  regu- 
lating the  globe  valve,  any  desired  pressures  in 
the  apparatus  can  be  secured. 

The  maximum  safe  steam  pressures  above 
atmosphere,  to  which  the  various  springs  made 
for  the  indicator  can  be  subjected,  are  given  in 
the  following  table: 


Scale  of  Spring. 

Maximum  Safe  Pressure 
to  Which  a  Spring-  can 
be  Subjected. 

8 

10 

10 

15 

12 

20 

16 

28 

20 

40 

24 

48 

30 

70 

32 

75 

40 

95 

48 

112 

50 

120 

60 

140 

64 

152 

80 

180 

100 

200 

120 

240 

150 

290 

FIG.  16. 


The  paper  drum  turns  on  a  vertical  steel 
shaft,  secured  at  the  lower  end  to  the  frame  of 
the  indicator.  The  drum  is  supported  at  the 
bottom  by  a  carriage,  which  has  a  long  vertical 
bearing  on  the  shaft.  It  is  guided  at  the  top  by 
the  same  shaft,  which  is  prolonged  for  this  pur- 
pose, the  drum  being  closed  in  at  the  top  and 
provided  with  a  central  bearing.  The  drum  is 
held  in  place  by  a  close  fit,  in  the  usual  manner, 
and  is  easily  removed  by  the  hand  when  desired. 
Stops  are  provided  on  the  inside  of  the  drum  at 
the  bottom,  with  openings  in  the  outside  of  the 

(10) 


138  CONSTRUCTION    OF   INDICATORS. 

carriage  to  correspond,  so  as  to  prevent  the 
drum  from  slipping-.  These  are  so  placed  that 
the  position  of  the  drum  may  be  changed  so  as 
to  take  diagrams  in  the  reverse  position  of  the 
pencil  mechanism,  when  so  desired.  The  drum 
is  made  of  thin  brass  tubing,  so  as  to  be  ex- 
tremely light.  Suitable  strength  is  obtained  by 
leaving  a  ring  of  thicker  metal  at  the  bottom  and 
by  employing  the  closed  top.  Steel  clips  are  at- 
tached to  the  drum  for  holding  the  paper. 

The  drum  carriage  projects  below  the  lower 
end  of  the  drum,  where  it  is  provided  with  a 
groove  for  the  reception  of  the  driving  cord. 
This  groove  has  sufficient  width  for  two  com- 
plete turns  of  the  cord.  The  drum  spring,  by 
which  the  backward  movement  of  the  drum  is 
accomplished,  consists  of  a  flat  spiral  spring  of 
the  watch  spring  type,  placed  in  a  cavity  under 
the  drum  carriage  encircling  the  bearing.  It  is 
attached  at  one  end  to  the  frame  below,  and  at 
the  other  end  to  the  drum  carriage.  In  its  normal 
position  the  drum  carriage  is  kept  against  a  stop 
by  means  of  the  pull  of  the  spring.  The  lower 
hub  of  the  drum  carriage  rests  directly  on  the 
spring  case,  while  the  opposite  hub  is  in  contact 
with  a  knurled  thumb  nut,  screwed  and  pinned 
to  the  drum  stud,  in  a  position  to  just  give  a 
slight  amount  of  end  motion  to  the  drum  car- 
riage. This  thumb  nut  also  serves  as  a  con- 
venient means  of  regulating  the  tension  of  the 
drum  spring,  as  by  loosening  the  nut  that  screws 
the  spring  case  to  the  arm  of  the  instrument,  said 
thumb  nut  can  be  turned  in  either  direction  until 
the  desired  tension  is  obtained,  and  then  again 
tightening  the  nut. 


CONSTRUCTION    OF    INDICATORS.  139 

A  simple  form  of  carrier  pulley  serves  to 
operate  the  driving-  cord  from  any  direction.  A 
single  pulley  is  mounted  within  a  circular  per- 
pendicular plate,  the  center  of  which  coincides 
with  the  center  of  the  driving-  cord.  This  center 
also  coincides  with  the  circumference  of  the 
pulley.  The  plate  can  be  turned  about  its  center 
so  as  to  swing-  the  pulley  into  any  desired  ang-ular 
position,  and  thereby  lead  the  cord  off  in  any  de- 
sired direction.  The  plate  is  held  by  a  circular 
frame,  which  serves  also  as  a  clamp,  and  the 
pulley  is  fixed  in  position  by  the  use  of  the  same 
nut  which  secures  the  frame  to  the  pulley  arm. 

Some  of  the  prominent  features  in  the  design 
and  construction  of  the  Tabor  indicator,  which 
are  noticeable  to  one  handling  the  instrument, 
may  be  mentioned: 

The  instrument  is  attached  by  means  of  a 
coupling  having  but  one  thread.  It  is  simple, 
like  a  common  pipe  coupling,  and  is  operated  by 
simply  turning  it  in  the  proper  direction,  without 
exercising  that  care  which  the  use  of  couplings 
having  double  threads  requires. 

The  indicator  cock  has  a  stop  which  limits  its 
range  in  either  direction  to  full  open  or  closed, 
and  also  has  holes  provided  for  the  release  of  all 
steam  that  may  remain  between  the  indicator 
piston  and  cock  after  operating. 

The  pressure  of  the  pencil  on  the  paper  drum 
is  regulated  by  means  of  a  screw,  which  passes 
through  a  projection  on  the  slot  plate,  and  strikes 
against  a  small  stop  provided  for  the  purpose, 
which  stands  on  the  frame.  This  screw  is 
operated  by  a  handle,  which  is  of  sufficient  size 
to  be  readily  worked  by  the  fingers,  and  which 


140  CONSTRUCTION    OF    INDICATORS. 

also  serves  as  a  handle  for  turning*  the  pencil 
mechanism  back  and  forth,  as  is  done  in  the  act  of 
taking-  diagrams.  The  handle  may  be  intro- 
duced and  worked  from  either  side,  so  as  to  use 
the  pencil  mechanism  on  either  side  of  the  paper 
drum. 

The  end  of  the  pencil  bar  is  shaped  in  the 
form  of  a  thin  tube  for  the  reception  of  the  pencil 
lead  or  metallic  marking-  point.  The  tube  is  split 
apart  on  the  side  and  yields  to  the  slig-ht  press- 
ure required  to  introduce  the  pencil,  which  can 
be  introduced  from  either  side,  so  as  to  mark  on 
either  side  of  the  paper  drum  desired. 

The  outside  of  the  instrument  in  all  its  parts, 
excepting-  the  pencil  bar  and  links  composing  the 
pencil  mechanism,  is  nickel  plated.  The  pencil 
mechanism  is  made  of  steel,  hardened  and  drawn 
to  a  spring-  temper,  with  blue  finish. 

Some  of  the  dimensions  of  the  parts  in  the 
instrument  of  standard  size  are  as  follows: 

Diameter  of  piston 0.7978  inches. 

Diameter  of  paper  drum 2.063 

Stroke  of  paper  drum 5.5 

Height  of  paper  drum 4. 

Number  of  times  pencil  mechanism 

multiplies  piston  motion 5. 

Rang-e  of  motion  of  pencil  point 3.25 

A  result  of  the  care  in  designing-  and  con- 
structing- these  instruments  is  a  reduction  of 
friction  to  the  least  possible  amount. 


CONSTRUCTION    OF    INDICATORS.  141 


CHAPTER  VII. 

THE   IMPROVED    VICTOR  REDUCING    WHEEL. 

Recent  improvements  in  the  Victor  reduc- 
ing wheel  make  it  near  absolute  perfection. 
Every  part  is  made  of  the  material  best  suited 
to  the  work,  and  each  joint  is  so  admirably  fitted 
that  its  lightness,  accuracy  and  durability  are 
only  equaled  by  the  convenience  and  facility 
with  which  it  may  be  applied  to  any  indicator, 
stroke  or  speed.  It  has  no  gears,  therefore  no 
grating-  action.  The  cord  wheel  revolves  on  a 
polished  spindle.  The  wheel  is  stationary,  and 
the  guide  pulley  is  moved  across  its  face  a  dis- 
tance equal  to  the  thickness  of  the  cord  for  each 
revolution,  so  that  the  cord  will  wind  evenly,  coil 
to  coil,  no  matter  in  what  direction  it  is  led. 

The  improved  Victor  aluminum  reducing 
wheel  is  made  in  two  patterns,  large  and  small. 
The  only  difference  in  these  patterns  lies  in  the 
diameter  of  the  main  cord  wheel.  The  large 
pattern  is  especially  intended  for  strokes  of  four 
feet  and  over,  and  will  give  perfect  satisfaction 
on  strokes  of  eight  feet.  There  are  several  in  use 
on  high  speed  engines,  but  for  this  work  the 
smaller  size  is  recommended,  and  guaranteed 
to  operate  perfectly  to  any  speed  met  with  in 
practice. 

Both  patterns  are  carried  in  stock,  with  special 
arms  D,  Fig.  17,  to  fit  all  makes  of  indicators. 

A  feature  of  the  Victor  wheel  is  its  extreme 
simplicity,  and  the  facility  with  which  it  may  be 
taken  apart  for  cleaning  and  replacing  springs. 


142  CONSTRUCTION   OF   INDICATORS. 

By  actual  timing-  the  instrument  has  been  taken 
apart,  a  spring-  replaced  and  assembled,  ready 
for  use  in  three  minutes. 

One  of  the  most  important  features  in  a  re- 
ducing- wheel  is  smooth  running-.  In  fact,  with- 
out it  an  accurate  diagram  cannot  be  secured. 
After  many  experiments  the  arrangement  em- 
ployed in  the  improved  Victor,  a  heavy,  braided 
linen  cord,  which  connects  the  small  pulley  E  to 
the  spring-  case  F,  Fig-.  17,  was  adopted. 


FIG.  17. 

This  method  transmits  the  power  of  the 
spring-  without  friction,  and  as  the  cord  is  always 
under  a  uniform  tension,  all  stretch  is  soon  elim- 
inated. When  worn  out  it  may  be  replaced  in  a 
moment  and  without  cost. 

The  spring  case,  F^  is  made  of  aluminum, 
and  is  deeply  grooved,  so  that  the  intermediate 
cord  can  never  ride,  and  is  perfectly  guided  at 
all  times. 

The  freedom  from  friction,  which  is  one  of 
the  most  pleasing  and  noticeable  features  of  the 
Victor  wheel,  insures  its  operation  with  much 


CONSTRUCTION    OF    INDICATORS.  143 

less  spring-  tension  than  others,  which  means 
longer  life  of  the  spring-. 

The  cord  wheel  revolves  on  a  polished  steel 
spindle,  so  that  a  nice  fit  may  be  made  and  main- 
tained, even  after  years  of  ordinary  use. 

The  improved  Victor  wheel  is  provided  with 
bushings  for  all  strokes.  These  bushings,  B, 
are  quickly  changed. 

It  is  manufactured  by  James  L.  Robertson  & 
Son,  204  Fulton  street,  New  York  city. 


144  CONSTRUCTION    OF    INDICATORS. 


CHAPTER  VIII. 

THE  IDEAL  REDUCING  WHEEL. 

The  object  of  the  reducing"  wheel  is  to  reduce 
accurately  the  motion  of  an  engine  cross-head  to 
that  required  for  a  paper  drum  of  an  indicator, 
and  to  give  the  required  length  of  diagram 
regardless  of  the  engine  stroke.  If  either  the 
indicator  or  reducing-  motion  is  not  correct,  the 
cards  are  useless  and  deceptive,  hence  the  first 
step  toward  obtaining-  the  true  state  of  affairs  in 
a  steam  cylinder  is  an  indicator  that  will  show 
both  the  true  pressure,  or  vacuum,  and  a  cor- 
rect reducing-  motion  by  which  diagrams  can  be 
taken,  so  that  an  intellig-ent  engineer  can  inter-, 
pret  them,  adjust  the  valves  and  figure  the  power 
developed. 

The  Ideal  reducing  wheel  is  made  of  alumi- 
num, brass  and  steel,  combining  strength  and 
lightness,  two  essential  features,  together  with 
first-class  workmanship. 

The  wheel  or  drum,  from  which  the  cord 
passes  to  the  cross-head  is  only  two  and  three- 
quarters  inches  in  diameter,  and  is  made  of 
aluminum.  The  coil  spring  for  the  take-up  is  in 
a  case  two  and  one-quarter  inches  in  diameter, 
and  connected  by  a  3  to  1  gear  with  the  cord 
wheel  spindle,  so  that  while  the  light  alumi- 
num cord  wheel  makes  three  revolutions,  the 
spring  makes  but  one.  The  spring  can  be  ad- 
justed to  any  desired  tension,  to  keep  the  cord 
taut  on  return  stroke.  The  cord  wheel  revolves 
on  a  steel  screw,  the  thread  of  which  is  the  same 


CONSTRUCTION    OF    INDICATORS.  145 

pitch  as  the  cord,  so  that  when  the  cord  is  drawn 
out  the  wheel  travels  as  -it  revolves.  By  this 
means  the  cord  is  wound  smoothly  on  the  drum 
and  passes  straight  through  the  guide  pulley. 

To  use  the  reducing  wheel  on  the  indicator, 
remove  the  carrier  pulley  from  the  indicator,  and 
put  the  wheel  on  in  place  of  it.  Pass  the  drum 
cord  around  the  small  disk  through  the  hole  and 
under  the  holder,  being  careful  to  see  that  the 
cord  is  wound  around  the  bushing  or  disk  from 
the  left,  as  shown  in  Fig.  18.  Before  attaching  hook 
see  that  cord  on  the  wheel  and  indicator  is  taut 
at  shortest  part  of  the  stroke,  and  that  it  will 


FIG.  18. 

pull  out  a  little  further  than  the  longest  part  of 
vStroke.  The  reducing  wheel  can  be  used  in  any 
place  where  it  is  most  convenient,  bearing  in  mind 
that  the  cord  from  it  to  the  cross-head  should  run 
in  a  straight  line.  In  unhooking  the  cord,  allow 
it  to  return  slowly  until  the  stop  reaches  the 
guide  pulley. 

Bushings  of  various  sizes  are  furnished  so 
that  cards  can  be  taken  from  any  length  of  stroke 
up  to  seventy-two  inches. 

Theldealreducingwheel  is  manufactured  only 
by  John  S.  Bushnell,  successor  to  Thompson  & 
Bushnell,  120-122  Liberty  street,  New  York  city. 


146  CONSTRUCTION    OF    INDICATORS. 


CHAPTER  IX. 

SARGENT'S  ELECTRICAL  ATTACHMENT  FOR  STEAM 
ENGINE  INDICATORS. 

In  making-  elaborate  tests  of  power  plants,  it 
has  heretofore  been  necessary  to  employ  as 
many  assistants  as  there  were  indicators  used, 
but  the  difficulty  of  securing-  simultaneous  action 
on  their  part  is  so  great  that  satisfactory  work 
is  rarely  obtainable,  and  more  certain  means  to 
that  end  are  now  considered  necessary. 

Mr.  Frederick  Sargent,  M.E.,  invented  and 
patented  an  electrical  device  applicable  to  an  in- 
dicator, by  means  of  which  any  number  of  in- 
struments can  be  operated  and  diagrams  taken 
at  the  same  instant  of  time,  simply  by  closing  an 
electric  circuit. 

Fig-.  19  shows  a  Crosby  indicator  fitted  with 
a  Sarg-ent  electrical  attachment. 

For  the  purpose  of  illustrating-  the  manner  of 
operating-  the  attachment,  assume  that  it  is  desir- 
able to  procure  simultaneous  diagrams  from  a 
compound  eng-ine,  taking-  cards  from  the  ends  of 
each  cylinder.  Attach  the  indicators  to  the  en- 
gine and  arrange  the  drum  motion  in  the  usual 
manner.  On  each  indicator  secure  the  electrical 
attachment  to  its  plate.  Make  the  connections 
with  the  battery,  having  all  of  the  several  magnets 
and  the  circuit  closer  in  series.  Place  the  paper 
upon  the  drum  and  bring  the  pencil  arm  into 
such  a  position  as  will  allow  the  latch  to  drop 
into  the  screw  eye. 

Press  the  armature  firmly  against  the  magnet 


CONSTRUCTION    OF    INDICATORS. 


147 


and  adjust  the  marking-  point  to  the  paper  in  the 
usual  manner.  The  sleeve  handle  must  be  un- 
screwed enough  to  allow  the  full  operation  of  the 
armature.  The  circuit  should  be  closed  and  the 
armature  tension  spring's  adjusted,  so  that  the 
connected  attachment  will  work  simultaneously. 
Everything-  should  now  be  in  readiness  to  take 
diagrams.  Connect  the  drum  motions,  open  the 
indicator  cocks,  and  as  soon  as  desirable  close 


FIG.  19. 


the  circuit,  and  instantly  all  of  the  pencils  will  be 
broug-ht  ag-ainst  the  papers  and  will  remain  there 
as  long-  as  the  circuit  is  kept  closed. 

In  order  to  put  on  new  papers,  diseng-ag-e  the 
drum  motions,  lift  the  latch  and  swing-  the  pencil 
arm  out  of  the  way. 

The  amount  of  battery  power  required  will 
vary  with  circumstances  and  will-rang-e  from  one 
to  two  or  more  cells  of  a  No.  2  Sampson  battery, 
or  its  equivalent. 


148  CONSTRUCTION    OF   INDICATORS. 

The  battery  for  operating-  the  attachment  is 
inclosed  in  a  neat  hardwood  box  with  a  suitable 
handle  for  carrying1  it,  and  is  sealed  so  as  to  pre- 
vent slopping-.  It  is  very  compact  and  portable, 
being-  at  the  same  time  extremely  active,  long- 
lived  and  especially  adapted  to  open  circuit  work. 

The  connections  to  the  indicator  attachments 
can  be  made  with  the  battery  without  opening 
the  box,  the  binding-  posts  being-  on  the  outside. 
This  battery,  with  a  quantity  of  suitable  wire 
for  making-  connections,  is  furnished  with  the 
attachment.  The  Sarg-ent  electrical  attachment 
is  manufactured  by  the  Crosby  Steam  Gag-e  and 
Valve  Co.,  Boston,  Mass. 


CONSTRUCTION    OF    INDICATORS.  149 


CHAPTER  X. 

AMSLER'S  POLAR  PLANIMETER,  WITH  DIRECTIONS 
FOR  USING  IT  ON  INDICATOR  DIAGRAMS. 

Fig-.  20  represents  the  No.  1  plani meter.  It 
is  the  simplest  form  of  the  instrument,  having 
but  one  wheel,  and  is  designed  to  measure  areas 
in  square  inches  and  decimals  of  a  square  inch. 
The  figures  on  the  roller  wheel  D  represent 
units,  the  graduations  on  the  wheel  represent 
tenths,  and  the  vernier  gives  the  hundredths. 

The  use  of  Amsler's  polar  planimeter  in  the 
measurement  of  indicator  diagrams  enables  one 


-        FIG.  20. 

to  measure  ten  cards  with  it  in  the  time  which 
would  be  required  to  measure  one  card  by  any 
other  method,  and  it  insures  the  utmost  accuracy 
in  the  work. 

The  planimeter  is  a  precise  and  delicate  in- 
strument, and  should  be  handled  and  kept  with 
great  care,  in  order  that  it  may  be  depended 
upon  to  give  correct  results.  After  using,  it 
should  be  wiped  clean  with  a  piece  of  soft  chamois 
skin. 

The  Amsler  polar  planimeter  is  manufact- 
ured by  the  Crosby  Steam  Gage  and  Valve  Co., 
Boston,  Mass. 


150  CONSTRUCTION   OF   INDICATORS. 


CHAPTER  XL 

THE   LIPPINCOTT    PLANIMETER. 

The  accompanying  engraving-,  Fig.  21,  repre- 
sents a  new  form  of  planimeter. 

It  will  be  noticed  that  the  wheel  has  a  knife 
edge,  and  is  free  to  move  on  its  shaft,  so  that 
there  can  be  no  slipping-  on  the  surface  upon 
which  it  moves,  giving-  the  same  results  when 
used  upon  the  roug-hest  table  as  upon  the  finest 
paper. 

As  the  rotary  movement  of  this  wheel  does 
not  register,  it  is  apparent  that  the  accuracy  of 


FIG.  21. 

the  instrument  will  not  be  affected  by  any  re- 
duction of  the  diameter  of  the  wheel  or  injury 
to  the  knife  edge.  This  is  one  of  the  most  im- 
portant points  to  be  considered  in  the  selection 
of  a  planimeter.  It  is  evident,  however,  that 
this  claim  is  only  made  possible  by  taking  the 
reading  from  the  hub  and  not  from  the  edge  of 
the  wheel.  The  possibility  of  a  vitiated  reading 


CONSTRUCTION    OF    INDICATORS,  151 

on  account  of  the  knife  edge  coming*  in  contact 
with  separate  scale,  is  also  avoided  thereby. 

With  the  Lippincott  planimeter  the  sliding-  is 
done  entirely  upon  the  shaft,  and  as  this  shaft  is 
made  of  glass  it  is  practically  frictionless. 

The  pivot  screw  is  made  hollow,  and  by 
means  of  a  small  knob  a  sharp  point  may  be  pro- 
truded for  convenience  in  setting-  to  the  card 
leng-th,  while  a  small  spiral  spring-  normally  holds 
it  in  a  protected  position  after  the  setting-  opera- 
tion has  been  completed. 

It  will  thus  be  seen  that  any  bending-  in  the 
tracer  point  would  be  compensated  for  in  every 
setting-,  and  could  therefore  occasion  no  error. 
This  is  a  most  important  improvement,  and 
guarantees  initial  and  continued  accuracy. 

Inside  the  glass  shaft  is  placed  the  scale, 
which  is  printed  upon  specially  prepared  paper, 
so  that  the  greatest  contrast  and  legibility  may 
be  insured.  The  ends  of  this  shaft  are  then 
hermetically  sealed  under  a  partial  vacuum,  so 
that  the  scale  can  never  become  discolored  or 
affected  by  the  atmosphere. 

The  plates  employed  in  printing-  these  scales 
are  engine  divided  and  mathematically  correct. 

Three  of  these  scale  tubes  are  provided  with 
the  instrument,  each  containing-  two.  different 
graduations,  so  that  the  mean  effective  pressure 
may  be  read  direct,  without  computation,  for  the 
following-  indicator  springs:  6,  8,  10,  12,  16,  20, 
24,  30,  32,  40,  50,  60,  80,  100,  120  and  150.  For 
instance,  if  it  is  required  to  ascertain  the  M. 
E.  P.  of  a  card  taken  with  an  80  spring-,  insert 
a  tube  containing  a  40  scale,  and  mentally 
double  the  reading1;  or  if  special  accuracy  is 


152  CONSTRUCTION    OF    INDICATOKS. 

desired,  trace  the  diagram  twice,  without  stop- 
ping, and  the  reading-  will  be  correct  for  an  80- 
pound  spring-. 

The  correct  reading-  for  a  20  spring-  may  be 
had  from  a  40  scale  also,  and  in  like  manner 
other  scales  may  be  used  with  different  spring's, 
which  is  more  desirable  than  to  encumber  the 
case  with  a  number  of  useless  scale  tubes. 

Any  special  graduation  will  be  furnished  to 
order. 

To  use  the  instrument,  select  a  tube  contain- 
ing a  scale  corresponding  to  spring  used  in  tak- 
ing the  card,  and  insert  same  in  the  clamp,  as  in 
Fig.  21,  after  which  the  clamp  screw  is  to  be 
tightened  sufficiently  to  prevent  the  tube  from 
being  easily  moved. 

Loosen  the  set  screw,  and  adjust  the  points 
to  the  exact  length  of  the  card.  The  set  screw 
should  then  be  firmly  tightened,  so  that  the 
tracer  bar  cannot  be  moved  in  the  frame  block. 

Having  fastened  the  card  upon  the  table  with 
thumb  tacks,  place  the  instrument  with  radial 
bar  at  right  angles  to  the  tracer  bar.  After  this 
move  the  tracer  point  down  to  point  7\  The  left 
hand  edge  of  the  wheel  hub  may  then  be  set  at 
zero,  either  by  moving  the  radial  point  /?  to  the 
right  or  left,  or  by  moving  the  wheel  on  the  shaft. 
After  the  instrument  is  properly  placed,  the 
tracer  point  should  trace  the  line  of  the  diagram 
to  the  left,  in  the  direction  taken  by  the  hands  of 
a  watch,  noting  carefully  that  the  wheel  does  not 
strike  at  either  end  of  the  shaft  in  making  the 
circuit. 

If  a  reading  is  desired  in  square  inches,  use  a 
40  scale  and  set  the  points  four  inches  apart. 


CONSTRUCTION   OF   INDICATORS.  153 

The  points  may  also  set  five  inches  apart  and  a 
50  scale  used,  or  six  inches  and  a  60  scale. 
The  latter  is  preferable  in  taking-  the  area  of 
large  figures. 

Use  no  oil  on  any  part  of  the  instrument,  and 
keep  the  glass  tube  perfectly  clean  with  tissue 
paper,  or  clean  chamois  skin.  The  wheel  should 
slide  with  perfect  freedom  from  one  end  of  the 
tube  to  the  other. 

This  instrument  is  packed  in  a  fine  morocco 
velvet  lined  case,  with  nickel  trimming's,  and 
every  one  is  guaranteed  perfectly  accurate.  It  is 
manufactured  by  James  L.  Robertson  &  Sons, 
204  Fulton  street,  New  York  city. 


(ii) 


154  CONSTRUCTION    OF    INDICATORS. 


CHAPTER  XII. 

THE   COFFIN    AVERAGING    INSTRUMENT    FOR    CALCU- 
LATING INDICATOR  DIAGRAMS. 

When  the  mean  effective  pressure  on  a  large 
number  of  diagrams  is  desired,  time  and  labor 
may  be  saved  by  the  employment  of  an  averaging 
instrument  or  planimeter,  an  instrument  de- 
signed to  measure  the  areas  of  irregular  figures. 
It  is  operated  by  moving  a  tracer,  with  which  it 
is  fitted,  over  the  line  of  the  diagram,  and  it 
records  the  area  upon  a  graduated  wheel. 

In  using  the  Coffin  averager,  the  grooved 
metal  plate,  /,  is  first  connected  to  the  board  upon 
which  the  apparatus  is  mounted,  in  the  position 
shown  in  the  cut,  being  held  in  place  by  a  thumb- 
screw applied  from  the  back  side.  The  indi- 
cator card  is  then  placed  under  the  clamps  Cand 
K,  which  may  be  sprung  away  from  the  board  a 
sufficient  amount  to  allow  the  card  to  be  intro- 
duced, and  the  card  is  moved  toward  the  left  into 
such  a  position  that  the  atmospheric  line  is  near 
to  and  parallel  with  the  lower  edge  of  the  station- 
ary clamp,  C,  while  the  extreme  left  hand  end  of 
the  diagram  is  even  with  the  perpendicular  edge 
of  the  clamp.  The  movable  clamp,  K,  which  is 
fastened  at  the  bottom  to  a  sliding  plate,  is  then 
moved  toward  the  left,  till  the  vertical  beveled 
edge  just  touches  the  extreme  right  hand  end  of 
the  diagram.  The  diagram  shown  in  the  cut 
represents  the  proper  location  which  should  ex- 
ist when  these  preliminary  adjustments  have 
been  completed.  The  slide  at  the  bottom  of 


CONSTRUCTION    OF    INDICATORS. 


155 


clamp  A'fits  closely,  so- that  the  application  of  a 
slig-ht  pressure  with  the  thumb  or  finger  is  re- 
quired to  displace  it. 


FIG.  22. 


The  beam  of  the  instrument  is  next  placed  on 
the  board,  with  the  pin  at  the  lower  end  resting- 
in  the  groove,  /,  and  the  weig-ht,  Q,  applied  to  the 
top  of  the  pin  so  as  to  keep  it  securely  in  place. 


156  CONSTRUCTION    OF   INDICATORS. 

The  tracer,  O,  is  moved  to  the  right  hand  end  of 
the  diagram  and  set  at  the  point  D,  on  the  line  of 
the  diagram,  where  the  clamp  K and  the  diagram 
touch  each  other.  Here  a  slight  indentation  is 
made  in  the  paper  by  pressing  the  finger  on  the 
top  of  the  tracer,  and  this  serves  as  a  starting 
point.  The  graduated  wheel  is  next  turned  so 
as  to  bring  its  zero  mark  to  the  zero  mark  on  the 
vernier.  The  instrument  is  now  ready  for 
operation.  The  tracer,  O,  is  carefully  moved 
over  the  line  of  the  diagram,  in  the  direction  of 
motion  of  the  hands  of  a  watch,  and  continued  till 
a  complete  circuit  is  made  and  the  tracer  finally 
reaches  the  starting  point,  D.  Keeping  an  eye 
on  the  wheel,  the  tracer  is  now  moved  upward  by 
sliding  it  along  the  edge  of  the  clamp  K,  until  the 
reading  on  the  wheel  returns  to  zero.  Another 
light  indentation  is  made  in  the  paper  to  mark  the 
new  position  which  the  tracer  occupies.  This 
point  is  represented  at  A  in  the  cut.  The  in- 
strument is  now  moved  away,  the  clamp  pushed 
back,  and  the  distance  between  the  two  points,  D 
and  A,  is  measured  by  employing  a  scale  corre- 
sponding to  the  number  of  the  spring  used  in  the 
indicator.  The  distance  thus  found  is  the  mean 
effective  pressure,  expressed  in  pounds  per 
square  inch  of  piston. 

The  Coffin  planimeter  determines  the  desired 
result  without  computation,  but  it  may  be  used 
also  for  determining  the  area  inclosed- by  the 
diagram.  This  area  is  given  by  the  reading  on 
the  graduated  wheel,  when  the  circuit  of  the 
diagram  has  been  made  and  the  tracer  reaches 
the  starting  point,  D.  The  wheel  has  fifteen 
main  divisions,  each  of  which  represents  one 


CONSTRUCTION    OF    INDICATORS.  157 

square  inch  of  area.  Each  division  has  five  sub- 
divisions, each  sub-division  representing-  one- 
fifth,  or  two-tenths,  of  a  square  inch  of  area. 
The  vernier  scale  enables  the  sub-divisions  to  be 
read  in  fiftieths,  each  of  these  fiftieths,  therefore, 
representing-  two-one-hundredths  of  a  square 
inch.  Having-  obtained  the  area  in  this  manner, 
the  mean  effective  pressure  may  be  computed 
by  dividing-  the  number  of  the  spring-  represent- 
ing-the  pressure  per  inch  in  heig-ht  by  the  leng-th 
of  the  diagram  (inches)  and  multiplying  the 
quotient  by  the  area  (square  inches).  In  first 
placing-  the  indicator  card  under  the  clamps, 
care  must  be  observed  that  the  ends  of  the  dia- 
gram set  a  little  away  from  the  edg-e  of  the  clamp, 
so  as  to  allow  for  one-half  the  diameter  of  the 
tracer,  and  to  bring-  the  center  of  the  tracer  over 
the  center  of  the  line  of  the  diagram. 


PART  IV. 
MISCELLANEOUS  TABLES. 


160 


MISCELLANEOUS    TABLES. 


PROPERTIES  OF  SATURATED  AMMONIA. 

CALCULATED    FROM  THE  ORIGINAL  FORMULA  OF  PROF.    DE 
VOLSON  WOOD,    BY  GEORGE  DAVIDSON,   M.E. 

Computed  especially  for  and  originally  published  in  Ice  and  Refriger- 
ation for  December,  1894. 


Tempera- 

Pressure, 

gd« 

41 

oi 

2s 

S_o 

5£  - 

ture. 

Absolute. 

3 

•SB 

•d 

o^"5 

0"°* 

, 

9 

I1 

> 

>•§•* 

3|f 

fjs 

3jJ 

S 

|| 

C 

en 

Q 

l« 

1* 

0 

OD  a 

§>!•§ 

°§- 

i*» 

!*•£ 

*s 

2  0  o 

U 

f 

I 

f& 

F 

fS-S 

|;,§ 

3  &S 

3  gj.2 

o  0*0 

pi 

'55.  So 

4>  4> 

HQ 

—40 

420.66 

1539.90 

10.69 

—4.01 

579.67 

24.388 

.02348 

.0410 

42.589 

—40 

39 

1 

1584.43 

11.00 

—3.70 

579.07 

23.735 

.02351 

.0421 

42.535 

39 

38 

2 

16!  JO.  03 

11.32 

—3.38 

578.42 

23.102 

.02354 

.0433 

42.483 

38 

87 

3 

1676.71 

11.64 

—3.06 

577.88 

22.488 

.02357 

.0444 

42.427 

37 

36 

4 

1724.51 

11.98 

—2.72 

577.27 

21.895 

.02359 

.0457 

42.391 

36 

-36 

425.66 

1773.43 

12.31 

—2.39 

576.68 

21.321 

.02362 

.0469 

42.337 

—35 

34 

6 

18*3.50 

12.66 

-2,04 

576.08 

20.763 

.02364 

.0482 

42.301 

34 

33 

7 

1874.73 

13.02 

-1.68 

575.48 

20.221 

.02366 

.0495 

42.265 

33 

32 

8 

1927.17 

13.38 

-1.32 

574.89 

19.708 

.02368 

.0507 

42.213 

32 

31 

9 

1980.78 

13.75 

—0.95 

574.39 

19.204 

.02371 

.0521 

42.176 

31 

—30 

430.66 

2035.69 

14.13 

—0.57 

573.69 

18.693 

.02374 

.0535 

42.123 

—30 

29 

1 

2091.83 

14.53 

—0.17 

573,08 

18.225 

.02378 

.0519 

42.052 

29 

28 

2 

2149.23 

14.92 

+0.22 

572.48 

17.759 

.02381 

.0563 

42.000 

28 

27 

3 

2207.94 

15.33 

+0.63 

571.89 

17.307 

.02384 

.0577 

41.946 

27 

26 

4 

2267.97 

15.76 

+1.05 

571.28 

16.869 

.02387 

.0593 

41.893 

26 

—25 

435.66 

2329.34 

16.17 

+1.47 

570.68 

16.446 

.02389 

.0608 

41.858 

-25 

24 

6 

2392.09 

16.61 

1.91 

570.08 

16.034 

.02392 

.0624 

41.806 

24 

23 

7 

2456.23 

17.05 

2.35 

569.48 

15.633 

.02395 

.0640 

41.754 

23 

22 

8 

2520.46 

17.60 

2.8 

568.88 

15.252 

.02398 

.0656 

41.701 

22 

21 

9 

2588.77 

17.97 

3.27 

568.27 

14.875 

.02401 

.0672 

41.649 

21 

—20 

440.66 

2657.23 

18.45 

+3.75 

567.67 

14.507 

.02403 

.0689 

41.615 

-20 

19 

1 

2727.17 

18.94 

4.24 

567.06 

14.153 

.02406 

.0706 

41.563 

19 

18 

2 

2798.62 

19.43 

4.73 

566.43 

13.807 

.02409 

.0725 

41.511 

18 

17 

3 

2871:61 

19.94 

5.24 

565.85 

13.475 

.02411 

.0742 

41.480 

17 

16 

4 

2946.17 

20.46 

5.76 

565.25 

13.150 

.02414 

.0760 

41.425 

16 

—15 

445.66 

3022.31 

20.99 

+6.29 

564.64 

12.834 

.02417 

.0779 

41.374 

—15 

14 

6 

3100.07 

21.53 

6.83 

564.04 

12.527 

.02420 

.0798 

41.322 

14 

13 

7 

3179.45 

22.08 

7.38 

563.43 

12.230 

.02423 

.0818 

41.271 

13 

12 

8 

3260.52 

22.64 

7.94 

568.  -82 

11.939 

.02425 

.0838 

41.237 

12 

11 

9 

3343.29 

23.22 

8.52 

562.21 

11.659 

.02428 

41  186 

11 

—10 

450.66 

3427.75 

23.80 

+9.10 

561.61 

11.385 

.02431 

.0878 

41.135 

—10 

9 

1 

3513.97 

24.40 

9.70 

560.99 

11.117 

.02434 

.0899 

41.084 

9 

8 

2 

3601.97 

25.01 

10.31 

560.39 

10.860 

.02437 

.0921 

41.034 

8 

7 

3 

3691.75 

25.64 

10,94 

559.78 

10.604 

.02439 

.0943 

41.000 

7 

6 

4 

3783.37 

26.27 

11.57 

559.17 

10.362 

.02442 

.0965 

40.950 

6 

—5 

455.66 

3876.  &> 

26.92 

12.22 

558.56 

10.125 

.02445 

.0988 

40.900 

—  5 

4 

6 

3972.62 

27.59 

+12.89 

557.94 

9.894 

.02448 

.1011 

40.845 

4 

3 

7 

4069.48 

28.26 

13.56 

557.33 

9.669 

.02451 

.10H4 

40.799 

3 

2 

8 

4168.70 

28.95 

14.25 

556.73 

9.449 

02454 

.1058 

40.749 

2 

1 

4269.90 

29.65 

14.95 

556.11 

9.234 

.02457 

.1083 

40.700 

1 

0 

460.66 

4373.10 

30.37 

+15.67 

555.50 

9.028 

.02461 

.1107 

40.650 

0 

+1 

1 

4478.32 

31  10 

16.40 

554.88 

8.825 

.02463 

.1133 

40.601 

+  1 

2 

4485.60 

31.84 

17.14 

554.27 

8.630 

.0246H 

.1159 

40.551 

2 

3 

'3 

4694.96 

32.60 

17.90 

553.65 

8.436 

.02469 

.1186 

40.502 

jj 

4 

4 

4806.46 

33.38 

18.68 

553.04 

8.250 

.02472 

.1212 

40.453 

4 

*  For  values  at  temperatures  higher  than  100°  F.  see  Wood's 
table  on  page  163. 


MISCI<:LLAN?:OUS  TABLES. 


161 


PROPERTIES  OF  SATURATED  AMMONIA. 

CALCULATED   FROM  THE  ORIGINAL  FORMULA  OF  PROF.  DE 

VOLSON  WOOD,  BY  GEORGE  DAVIDSON,   M.E. 
Computed  especially  for  and  originally  published  in  Ice  and  Refriger- 
ation for  December,  1894. 


Tempera- 
ture. 

Pressure, 
Absolute. 

Gauge  Pressure, 
Pouud  per  Sq. 
Inch. 

111 

id* 

iji 

j15 

!&* 

W 

p 

n 

m 

Temperature. 
Degrees  F.  |l 

EL. 

Absolute. 
T, 

f* 

m 

| 

+5 

465.66 

4920.11 

34.16 

+19.46 

552.43 

8.070 

02475 

1240 

40.404 

+5 

6 

6 

5035.95 

4.97 

20.27 

651.81 

7.892 

02478 

1267 

40.355 

6 

7 

7 

5153.99 

5.79 

21.09 

551.19 

7.717 

02480 

1296 

40.322 

7 

8 

8 

5274.28 

6.63 

21.93 

550.58 

7.553 

02483 

1324 

40.274 

8 

9 

9 

5396.83 

7.48 

22.78 

549.96 

7.388 

02486 

1353 

40.226 

9 

flO 

70.66 

5521.71 

38.34 

+23.64 

549.35 

7.229 

02490 

1383 

40.160 

+10 

11 

1 

6649.48 

9.23 

24.53 

548.73 

7.075 

02493 

1413 

40412 

11 

12 

2 

5778.50 

4043 

25.43 

548.11 

6.924 

02496 

1444 

40.064 

12 

13 

3 

5910.52 

1.04 

26.34 

547.49 

6.786 

02499 

1474 

40.016 

13 

14 

4 

6044.96 

1.98 

27.28 

546.88 

6.632 

02502 

1507 

39.968 

14 

+15 

475.66 

6182.00 

42.94 

+28.24 

546.26 

6.491 

02505 

1541 

39.920 

+16 

16 

6 

6321.24 

3.90 

29.20 

545.63 

6.355 

02508 

1573 

39.872 

16 

17 

7 

6463.24 

44.88 

3048 

545.01 

6.222 

02511 

1607 

39.872 

17 

18 

8 

6607.77 

45.89 

3149 

544.39 

6.093 

02514 

1641 

<J9.777 

18 

19 

9 

6754.90 

46.91 

32.21 

543.74 

5.966 

02517 

4676 

39.729 

19 

+20 

480.66 

6904.68 

47.95 

+33.25 

543.15 

5.843 

02520 

.1711 

39.682 

+20 

21 

1 

7057.15 

49.01 

34.31 

642.53 

5.722 

02523 

1748 

39.635 

21 

22 

2 

7211.33 

50.09 

35.39 

541.90 

5-.  605 

02527 

.1784 

39.572 

22 

23 

3 

7370.27 

51.18 

36.48 

641  38 

5.488 

.0^539 

4822 

39.541 

23 

4 

7530.96 

52.30 

37.60 

540.66 

5.378 

.02533 

.1860 

39.479 

24 

+26 

485.66 

7694.52 

5343 

+38.73 

540.03 

5.270 

.02536 

4897 

39.432 

+25 

26 

6 

7860.89 

54.59 

39.89 

539.41 

5.163 

.02539 

493; 

39.386 

26  , 

27 

7- 

8030-16 

55.76 

41.06 

538.78 

6.068 

.02542 

4977 

39.339 

27  J 

88 

8 

8202.38 

66.96 

42.26 

538.16 

4.960 

.02545 

.2016 

39.292 

28 

29 

9 

8377-56 

5847 

43.47 

537.63 

4.858 

.02548 

.2059 

39.246 

29 

+30 

490.66 

8555.74 

59.42 

+44.72 

536.91 

4.763 

.02551 

.2099 

39.200 

+30 

31 

1 

8736.96 

60.67 

45.97 

536.28 

4.668 

.02554 

.2142 

39415 

31 

32 

2 

8921.26 

61.95 

47.25 

535.66 

4.577 

.02557 

.2185 

39408 

32 

33 

3 

9108.71 

63.25 

48.55 

535.03 

4.486 

.02561 

.2229 

39.047 

33 

34 

4 

9299.32 

64.58 

49.88 

534.40 

4.400 

.02664 

.2273 

39.001 

34 

+35 

495.66 

9493.07 

65.92 

+51.22 

533.78 

4.314 

-.02568 

.2318 

38.940 

+35 

36 

6 

9690.04 

67.29 

52.59 

633.13 

4.234 

.02571 

.2362 

38.894 

36 

37 

7 

9890.  75 

68.68 

53.98 

532,52 

4.157 

.02574 

.2413 

38.850 

37 

38 

8 

10093.91 

70.09 

55.39 

531.89 

4  O68 

.02578 

.245!- 

38.789 

38 

39 

9 

10300.88 

71.53 

56.83 

531.26 

3.989 

02582 

.2507 

38.729 

39 

+40 

500.66 

10511.16 

72.99 

+68.29 

530.63 

3  915 

.02586 

.2554 

38  684 

+40 

41 

1 

10724.95 

74.48 

59.78 

529.99 

3.839 

.02588 

.2606 

38.639 

41 

42 

2 

10942.18 

75.99 

61.29 

529.36 

3.766 

.02591 

.2655 

3S.595 

42 

43 

3 

11162.93 

77.52 

62.82 

528.73 

3.695 

.02594 

.2706 

38.550 

43 

44 

4 

11387.21 

79.08 

64.38 

528.10 

3.627 

.03597 

.2757 

33.499 

4<J 

+45 

505.66 

11615.12 

80.66 

+65.96 

527.47 

3  559 

.0260( 

.2809 

38  461 

+45 

46 

6 

11846.64 

82.27 

67.5'i 

526.83 

3  493 

02603 

286* 

38  41" 

46 

47 

12081  80 

83.90 

69.20 

526.20 

3.428 

.02606 

.291" 

38.373 

47 

41 

8 

12320.71 

85.56 

70.8fi 

52557 

3.362 

.0^609 

.2974 

38.328 

48 

49 

9 

12563.36 

87.2o 

72.56 

524  93 

3  303 

.02612 

.302~ 

38.284 

49 

4-50 

510.66 

12809.91 

.88.96 

+74.26 

524  3( 

3.242 

.02616 

.3084 

38.22h 

4-50 

"'  5 

1 

13U80.21 

90.7 

76  OC 

r>23  6h 

3.182 

.02620 

.3143 

38  167 

51 

52 

2 

13314.43 

92.4 

77  7f 

>23  03 

3  124 

02623 

3201 

3«  124 

52 

63 

8 

13572.52 

94  2 

79.55,522.39 

3  069 

0262fi 

.3258 

3*  080 

53 

54 

4 

13834.6 

96.0 

81.3?|521.7fi 

3.012 

.0262S 

.3220 

38  037 

54 

162 


MISCELLANEOUS    TABLES. 


PROPERTIES  OF  SATURATED  AMMONIA. 

CALCULATED   FROM  THE  ORIGINAL  FORMULA  OF  PROF.   DE 
VOLSON  WOOD,    BY  GEORGE  DAVIDSON,    M.E. 

Computed  especially  for  and  originally  published  in  Ice  and  Refriger- 
ation for  December,  1894. 


Tempera- 

Pressure, 

g  a> 

g*3 

5 

Si 

£S 

-»$ 

ture. 

Absolute. 

*™ 

|| 

M 

JP.£ 

2p 

"j  </3  *J 

'  8? 

hi 

®t 

»"§ 

O  Q< 

^EH^ 

$£ 

**  D+^ 

>a3 

'-'•ac 
.^_  c  o 

P 

*~  ' 

CO 

9 

i 

!* 

|l 

%* 

*"•%  . 

**J 

la* 

M 

!r 

||s 

& 

f 

1 

|* 

£ 

Ill 

o 

p 

11 
1 

in 

III 

°S.5w> 

Stt 

+65 

515.66 

14100.74 

97.92 

+83.22 

521.12 

2.958 

.02632 

3380 

37.994 

+55 

6« 

6 

14370.92 

99.80 

85.10 

520.48 

2.905 

.02630 

.344237.936 

rxj 

57 

7 

14645.18 

101.70 

87.00 

519.84 

2.853 

.02639 

.3505 

37.893 

57 

58 

8 

14923.98 

103.64 

88.94 

519.20 

2.802 

.02643 

.  3568 

07.835 

59 

9 

15206.28 

105.60 

90.90 

618.57 

2.753 

.02646 

.3632 

37.793 

59 

+60 

520.66 

15493.09 

107.59 

+92.89 

517.93 

2.705 

.02651 

.3697 

37.736 

+60 

61 

1 

15784.23 

109.61 

94.91 

517.29 

2.658 

.02654 

.3762 

37.678 

61 

62 

2 

16079.67 

111.66 

96.96 

516.65 

2.610 

.02C58 

.3831 

37.622 

62 

63 

3 

16379.51 

113.75 

99.05 

516.01 

2.565 

.02661 

.3898 

37.579 

63 

64 

4 

16683.76 

115.86 

101.16 

515.37 

2.520 

.02665 

.39(58 

37.523 

64 

+65 

525.66 

16992.50 

118.03 

+103.33 

514.73 

2.476 

.02668 

.4039 

37.481 

+65 

66 

6 

17305.70 

120.  18 

105.48 

514.09 

2.433 

.026711.4110 

37.43M 

67 

7 

17623.45 

122.38 

107.68 

513.45 

2.389 

.02675.4189 

37.383 

67 

68 

8 

17946.89 

124.62 

109.92 

512.81 

2.351 

.02678 

.4254 

37.341 

(is 

69 

9 

18272.81 

126.89 

112.19 

512.16 

2.310 

.02682 

.4329 

37.285 

69 

+70 

530.66 

18604.53 

129.19 

+114.49 

511.52 

2.272 

.02686 

.4401 

37.231 

+70 

71 

1 

18941.00 

131.54 

116.8* 

510.87 

2.233 

.02689 

.4479 

37.188 

71 

72 

2 

19282.21 

133.90 

119.20 

510.22 

2.194 

.02693 

.4558 

37.133 

72 

73 

3 

19628.32 

136.31 

121.61 

509.58 

2.153 

.02697 

.4645 

37.079 

73 

74 

4 

19979.22 

138.74 

124.04 

508.93 

2.122 

.02700 

.4712 

37.037 

74 

+75 

535.66 

20335.16 

141.22 

+126.  52 

508.29 

2.087 

.02703 

.4791 

36.995 

+75 

76 

6 

20696.00 

143.  72 

129.02 

507.64 

2.052 

.027« 

.4873 

36.954 

76 

77 

7 

21061.85 

146.26 

131.56 

506.99 

2.017 

.02710 

.4957 

36.900 

77 

78 

8 

21432.82 

148.84 

134.14 

506.34 

1.995 

02714 

.5012 

36.845 

78 

79 

9 

21808.85 

151.45 

136.76 

605.69 

1.952 

02717 

.5123 

36.805 

79 

+80 

510-66 

.32190.15 

154.10 

+139.40 

505.05 

1.921 

02721 

.5205 

36.751 

+80 

81 

1 

22576.51 

166.78 

142.08 

504.40 

1.889 

02725 

.5294 

36.696 

81 

82 

2 

22968  '.88 

159.50 

144.80 

503.75 

1.858 

02728 

.5382 

36.657 

82 

83 

3 

23365.38 

162.26 

147.56 

503.10 

1.827 

02732 

.5473 

36.603 

K3 

84 

4 

23767.81 

165.05 

150.35 

502.45 

1.799 

02736 

.5558 

36.549 

84 

+85 

545.66 

24175.61 

167.88 

+153.18 

501.81 

1.770 

02739 

.5649 

36.509 

+85 

86 

6 

24588.92 

170.75 

156.05 

501.15 

1.741 

02743 

.5744 

36.456 

86 

87 

7 

25007.80 

173.66 

158.96 

500.50 

1.714 

02747 

.5834 

36.407 

87 

88 

8 

25432.16 

176.61 

161.91 

499.85 

1.687 

02751 

.5927 

36.350 

88 

89 

9 

25862.14 

179.69 

164.89 

*99.20 

1.660 

02754 

.6024 

36.311 

89 

+90 

550.66 

26297.88 

182.62 

+167.92 

498.55 

1.634 

02758 

.6120 

36.258 

+90 

91 

26739.88 

185.69 

170-99 

97.89 

1.608 

02761 

.6219 

86.219 

91 

92 

2 

27186.56 

188.79 

174.09 

497.24 

1.5H3 

02765 

.6317 

36.166 

92 

93 

3 

27639.43 

191.94 

177.24 

496.59 

1  .558 

.02769 

.6418 

35.114 

93 

04 

4 

28098.26 

195  13 

180.43 

95.94 

1.534 

.02772 

6518 

36.075 

94 

+95 

555.66 

28563.00 

198.  35 

+  183.  (15 

95".  29 

1.510 

.02776 

6622 

36.025? 

+95 

96 

6 

29033.86 

201.62 

186.92 

94.63 

1.486 

.02780 

6729 

35  971 

97 

f 

29510.69 

204.94 

190.24 

93.97 

1.463 

02784 

6835 

55.919 

97 

98 

8 

9993.52 

208.29 

193.59 

93.32 

1.442 

.02787 

6934 

35.881 

98 

99 

9 

{0482.52 

211.68 

196.98 

92.66 

419 

.02791 

7047 

35.829 

99" 

MOO 

560.60 

W977.78 

215.12 

+200.42 

92.01 

.398 

.02795 

7153 

35.778 

+  100 

MISCELLANEOUS    TABLES. 


163 


WOOD'S  TABLE   OF  PROPERTIES    OF    SATUR- 
ATED VAPOR  OF  AMMONIA. 


Temperature 

Pressure 

i  ' 

== 

o 

•o 

W    go 

Absolute. 

If  — 

tJ  2 

*    CD 

ar- 

\- 

•X*  '"D 

£ 

S 

|| 

I! 

II 

«H<5 

S'l 

51 

*  . 

f* 

2 

£ 
h 

£ 

k 

*^g 

f| 

"3  "5 

£s 

*       °j0 

ow 

•3 

o| 

§ 

a 

a 

ft 

®  (3 

2a> 

S*^ 

a~ 

^  * 

I 

I 

2- 

.s 

1= 

"*X3 

ca 

ll 

ii 

So 

Q 

^ 

H 

i_3 

tf 

i 

>• 

t> 

? 

—  40 

420.66 

1540.9 

10.69 

579.67 

48.23 

531.44 

24.37 

.0234 

0410 

—  35 

425.66 

1773.6 

12  31 

576.69 

48.48 

528.21 

21.29 

.0236 

.0467 

—  30 

430.66 

2035.8 

14.13 

573.69 

48.77 

524.92 

18.66 

.0237 

0535 

-  25 

435.66 

2329.5 

16.17 

570.68 

49  06 

521.62 

16.41 

.0238 

.0609 

-20 

440.66 

2657.5 

18.45 

567.67 

49.38 

518.29 

14.48 

.0240 

.0690 

—  15 

445.66 

8022.5 

20.99 

564.64 

49.67 

514  97 

12.81 

0242 

.0779 

—  10 

450.66 

3428.0 

23.77 

561.61 

49.99 

511.62 

11.36 

.0243 

.0878 

—    5 

455.66 

3877.2 

26.93 

558.56 

50.31 

508.25 

10.12 

.0244 

.0988 

0 

460.66 

4373.5 

30.37 

555.50 

50.68 

504.82 

9.04 

0246 

.1109 

+    5 

465.66 

4920.5 

34.17 

552.43 

50.84 

501.59 

8.06 

0247 

.1241 

+  10 

470.66 

5622.2 

38.55 

549.35 

51.13 

498.22 

7.23 

0249 

.1384 

+  15 

475.66 

6182.4 

42.93 

546.26 

61.33 

494.93 

9.49 

.0250 

.1540 

+  20 

480.66 

6905.3 

47.95 

543.15 

51.61 

491.54 

5.84 

.0252 

.1712 

+  25 

485.66 

7695.2 

53.43 

540.03 

51.80 

488.23 

5.26 

.0253 

.1901 

+  30 

490.66 

8556.6 

59.41 

536.92 

52.01 

484.91 

4  75 

.0254 

.2106  ' 

+  35 

495.66 

9493.9 

65.93 

533.78 

52.22 

481.56 

4.31 

.0256 

.2320 

+  40 

500.66 

10512 

73.00 

530.63 

52.42 

478.21 

3  91 

.0257 

.2583 

+  45 

505.66 

11616 

80.66 

527.47 

52.62 

474.85 

3.56 

.0260 

.2809 

+  50 

510.66 

12811 

88.96 

•524.30 

52.82 

471.48 

3.25 

.0260 

.3109 

+  55 

515.66 

14102 

97.93 

521.12 

53.01 

468.11 

2.96 

.0260 

.3379 

+  60 

520.66 

15494 

107.60 

517.93 

53.21 

464.72 

2.70 

.0265 

.3704 

+  65 

525.66 

16998 

118.03 

514.73 

53.38 

461.35 

2  48 

.0266 

.4034 

+  70 

530.66 

18605 

129.21 

511.52 

53.57 

457.85 

2.27 

.0268 

.4405 

+  75 

535.66 

20336 

141.25 

608.29 

53.76 

454.53 

2  08 

.0270 

.4808 

+  FO 

540.66 

22192 

154.11 

504.66 

53  96 

450.70 

1.91 

.0272 

.5262 

+  85 

545.66 

24178 

167.86 

501  81 

54,15 

447  66 

1.77 

.0273 

.5649 

+  90 

550.66 

26300 

182.8 

498  ..11 

54.28 

443.83 

1.64 

.0274 

.6098 

+  95 

555.66 

28565 

198.37 

495.29 

54.41 

440.88 

1.51 

.0277 

6622 

+100 

560.66 

30980 

215.14 

491.50 

54.54 

436.06 

1.39 

.0271) 

.7194 

+105 

565.66 

33550 

232.98 

488.72 

54.67 

434.08 

1.289 

.0281 

.7757 

+110 

570.66 

36284 

251.97 

485.42 

54.78 

430.64 

1.203 

.0283 

.8312 

+115 

575.66 

39188 

272.14 

482.41 

54.91 

427.40 

1.121 

.0285    .8912 

+120 

580.66 

42267 

293.49 

478.79 

55.03 

423.75 

1.041 

.0287 

.9608 

+125 
+  130 

585.66 
590.66 

45528 
48978 

316.16 
340.42 

475.45 
472.11 

55.09 
65.16 

420.39 
416.94 

.9699 
.9051 

0289)1.0310 
.0291  1.1048 

+135 

595.66 

52626 

365.16 

468.75 

55.22 

413.53 

.8457 

.02931.1824 

+140 

600.66 

56483 

392.22 

465.39 

55.29 

410.09 

.7910 

.02951.2642 

+145 

605.66 

60550 

420.49 

462.01 

65.34 

406.67 

.7408 

.0297 

1.349? 

+160 

610.  6tf 

64833 

450.20 

458.62 

55.39 

402.23 

.6946 

.0299 

1.4396 

+155 

615.66 

69341 

481.54 

455.22 

55.43 

399  79 

.6511 

0302I1.535S 

+  160 

620.66 

71086 

514.40 

451.81 

55.46 

39R.H5 

.6128 

.0304 

1.6318 

+165 

625.66 

79071 

549.  04  1  448.39 

55.48    392.94      .5765 

.0306 

1.7344 

Thfe  critical  pressure  of  ammonia  is  115  atmospheres,  the 
critical  temperature  at  130°  F.  (Dewar),  critical  volume  .00482 
(calculated). 


164 


MISCELLANEOUS    TABLES. 


TABLE     OF    AMMONIA    GAS     (SUPER-HEATED 
VAPOR).     TEMPERATURE  IN  DEGREES  F. 

11 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

No.  of  Cu.  Ft.,  v,  Approximately  Contained  in  ILb.  of  Gas. 


15 

18.81 

19.05 

19.20 

19.48 

19.68 

19.87 

20.08 

20.2520.544 

20. 

16 

17.56 

17.85 

18.09 

18.24 

18.43 

18.52 

18.81 

18.9019.20 

19. 

17 

16.60 

16.70 

16.96 

17.08 

17.28 

17.48 

17.66 

17.8518.09 

18. 

18 

15.54 

15;  84 

15.93 

16.12 

16.32 

16.51 

16.70 

16,8917.08 

17. 

19 

14.78 

14.97 

15.18 

15.26 

15.45 

15.64 

15,84 

15.93 

16.12 

10. 

20 

14.01 

14.25 

14.40 

H.49 

14.  6g 

14.88 

14.97 

15.16 

15.36 

15. 

21 

13.34 

13.53 

13.63 

13.82 

14.01 

14.11 

14.30 

14.40jl4.59 

14. 

22 

12.76 

12.86 

13.05 

13.15 

1334 

13.44 

13.63 

13.7213.92 

14. 

23 

12.19 

12.28 

12.48 

12.57 

12.76 

12  86 

13.05 

13.1513.34 

13. 

1 

24 

11.71 

11.80 

11.90 

12.09 

12.19 

12.38 

12.48 

12.57jl2.76 

12. 

25 

11.23 

11.34 

11.42 

11.61 

11.  Til  11.80 

11.90 

12  0912.19 

12. 

26 

10.75 

10.84 

11.04 

11.13 

11.23 

11.32 

11.62 

11.6111.71 

11. 

27 

10.36 

10.46 

10.56 

10.75 

10.84 

10.94 

11.01 

11.2311.32 

11. 

2s 

9.98 

10.08 

10.17 

10.36 

10.46 

.10.56 

10.65 

10.75 

10.84 

10. 

29 

9.60 

9.69 

9.79 

9.98 

10.08 

10.17 

10.27 

10.36 

10.46 

10. 

30 

9.2120 

9.30 

10.46 

9.60 

9.69 

9.79 

9.98 

10.08 

10.17 

10. 

31 

8.84 

9.12 

9.21 

9.31 

9.40 

9.50 

9.60 

9.69 

9.KO 

9. 

32 

8.83 

8.93 

9.02 

9.12 

».21 

9.31 

9.40 

9.50 

9. 

33 

8.54 

8.64 

8.73 

8.83 

8.91 

9.02 

9.11 

9.21 

9. 

34 

8.25 

9.35 

8.49 

8.54 

8.64 

8.73 

8.83 

8.92 

9. 

35 

8.16 

8.25 

8.35 

8.44 

8.54 

8.64 

8.64 

8. 

33 

•-. 

7.87 

7.96 

8.06 

8.16 

8.2tf 

8.35 

8.44 

8. 

37 

>  7.68 

7.67 

7.87 

7.96 

8.06 

8.16 

8.26 

8. 

38 

7,48 

7.58 

7.68 

7.77 

7.77 

7.8! 

7.98 

8. 

3!) 

7.39 

7.48 

7.48 

7.58 

7.68 

7.77 

7. 

4(1 

7.20 

7.29 

7.39 

7.39 

7.48 

7.58 

7. 

41 



7.00 

7.10 

7.20 

7.20 

7.29 

7.39 

7. 

42 

6.81 

6.91 

7.00 

7.10 

7.10 

7.20 

7'. 

43 

6.72 

6.81 

6.91 

7.00 

7.08 

7. 

44 

6.52 

6.62 

6.72 

6  81 

6.91 

45 

6.43 

6.52 

6.62 

6.62 

6.72 

6. 

I 

MISCELLANEOUS   TABLES. 


165 


TABLE   SHOWING   REFRIGERATING   EFFECT    OF  ONE    CUBIC 

FOOT  OF  AMMONIA  GAS  AT  DIFFERENT  CONDENSER 
AND  SUCTION  (BACK)  PRESSURES  IN  B.  T.  UNITS. 


o  . 

*• 

Temperature  of  the  Liquid  in  Degrees  F. 

•gfc 

g  s.S 

65°      70°        75°        80°        85°        90°      95°      100°    105° 

D  (U 

1J«? 

-t->  be 

W*1  a! 

$  a  a 

|c 

Ifj 

Corresp'g.  Condenser  Pressure  (gauge),  Ibs.  per  sq.  in. 

8 

H 

°c^ 

103       115      127       139       153       168      184       200       218 

G.  Pres. 

—27° 

1 

27.30 

27.01 

26.73 

26.44 

26.16 

25.87 

25.59 

25.30 

25.02 

—20° 

4 

33.74 

33.40 

33.04 

32.70 

32.34 

31.99 

31.64 

31.30 

30.94- 

—15° 

6 

36.36 

3B.48 

36.10 

35.72 

35.34 

34.96 

34.58 

34.20 

33.82 

—10° 

9 

42.28 

41.84 

41.41 

40.97 

40.54 

40.10 

39.67 

39.23 

38.80 

—  5° 

13 

48.31 

47.81 

47.32 

46.82 

46.33 

45.83 

45.34 

44.84 

44.35 

0° 

16 

54.88 

54.32 

53.76 

53.20 

52.64 

52.08 

51.52 

50.96 

50  40 

5° 

20 

61.50 

60.87 

60.25 

59.62 

59.00 

58.37 

57.75 

57.12 

56.60 

10° 

24 

68.66 

67.97 

67.27 

66.58 

65.88 

65.19 

64.49 

63.80 

83.10 

15° 

28 

75.88 

75.12 

74.35 

73.59 

72.82 

72.06 

71.29 

70.53 

69.76 

20° 

33 

85.15 

84.30 

83.44 

82.59 

81.73 

80.88 

80.02 

79.17 

78.31 

25° 

39 

95.50 

94.54 

93.59 

92.63 

91.68 

90.72 

89.97 

88.81 

87.86 

30° 

45 

106.21 

105.15 

104.09 

103.03 

101.97 

100.91 

99.85 

98.79 

97.73 

35° 

51 

115.69  114.54  123.39 

112.24 

111.09 

109.94 

108.79107.64 

106.49 

TABLE  GIVING  NUMBER  OF  CUBIC  FEET  OF  GAS  THAT  MUST 

BE  PUMPED  PER  MINUTE  AT  DIFFERENT  CONDENSER 

AND   SUCTION    PRESSURES,  TO    PRODUCE   ONE  TON 

OF  REFRIGERATION  IN  TWENTY-FOUR  HOURS. 


§ 

Temperature  of  the  Gas  in  Degrees  F. 

O   . 

v«  ^      * 

q  P  .5 

65°        70°        75°        80°        85°        90°      95°      100°    105° 

g| 

II? 

ft 

f|| 

Corresp'g.  Condenser  Pressure  (gauge;,  Ibs.  per  sq.  in. 

1" 

°lj 

103       115      127        139       153       168      184       200       218 

27° 

G.  Pres. 

7.22 

7.3 

7.37 

7.46 

7.54 

7.62 

7.70 

7.79 

7.88 

—20° 

4 

5.84 

5.9 

5.96 

6.03 

6.09 

6.16 

6.23 

6.30 

6.43 

—15° 

6 

5.35 

5.4 

5.46 

5.52 

5.58 

5.64 

5.70 

5.77 

5.83 

-10° 

9 

4.66 

4.73 

4.76 

4.81 

4.86 

4.91 

4.97 

5.05 

5.08 

-  5° 

13 

4.09 

4.12 

4.17 

4.21 

4.25 

4.30 

4.35 

4.40 

4.44 

0° 

16 

3.59 

3.63 

3.66 

3.70 

3.74 

3.78 

3.83 

3.87 

3.91 

5° 

20 

3.20 

3.24 

3.27 

3.30 

3.34 

3.38 

3.41 

3.45 

3.49 

10° 

24 

2.87 

2.9 

2.93 

2.96 

2  99 

3.02 

3.06 

3.09 

3.12 

15° 

28 

2.59 

2.61 

2.65 

2.68 

2.71 

2.73 

2.76 

2.80 

2.82 

20° 

33 

2.31 

2.34 

2.36 

2.38 

2.41 

2.44 

2.46 

2.49 

2.51 

25° 

39 

2.06 

2.08 

2.10 

2.12 

2.15 

2.17 

2.20 

2.22 

2.24 

30° 

45 

1.85 

1.87 

1.89 

1.91 

1.93 

1.95 

1.97 

2.00 

2.01 

35° 

51 

1.70 

1.72 

1.74 

1.76 

1.77 

1.79 

1.81 

1.83 

1.85 

166  MISCELLANEOUS   TABLES. 

ANHYDROUS    AMMONIA. 

Ammonia  is  a  compound  of  one  volume  of 
nitrogen  with  three  volumes  of  hydrogen,  and 
is  therefore  represented  by  the  chemical  form- 
ula NH3.  It  contains  by  weight  82.35  per  cent 
nitrogen  and  17.65  per  cent  hydrogen.  Its  mole- 
cular weight  is  17. 

Ammonia  is  a  colorless  gas  possessing  a  very 
characteristic  pungent  smell.  It  is  much  lighter 
than  air,  having  a  specific  gravity  (air  1)  of  0.586, 
one  liter  of  gas  weighing,  at  the  normal  temper- 
ature and  pressure,  0.76193  grams.  By  mechan- 
ical pressure  and  cooling,  it  is  converted  from 
a  gaseous  to  a  liquid  state  (liquid  anhydrous  am- 
monia) which  boils  under  the  ordinary  atmos- 
pheric pressure  at  28T60°  below  zero,  or  240^° 
lower  than  the  boiling  point  of  water  under  the 
same  conditions.  One  pound  of  the  liquid  at  32° 
will  occupy  21.017  cubic  feet  of  space  when 
evaporated  at  the  atmospheric  pressure.  The 
specific  heat  of  ammonia  gas,  as  determined  by 
Regnault  (capacity  for  heat),  is  0.50836.  Its 
latent  heat  of  evaporation  is  about  560  thermal 
units  at  32°  Fahrenheit,  at  which  temperature 
one  pound  of  the  liquid,  evaporated  under  a 
pressure  of  fifteen  pounds  per  square  inch,  will 
occupy  twenty-one  cubic  feet. 


TESTING    ANHYDROUS    AMMONIA. 

Usually  ammonia  manufacturers  sell  their 
goods  subject  to  the  condition  and  agreement, 
on  the  part  of  the  purchaser,  that  a  sample  be 
drawn  from  each  cylinder  upon  arrival  and  sub- 
jected to  a  test  before  emptying  the  contents, 


MISCELLANEOUS    TABLES.  167 

no  reclamation  being-  allowed  on  account  of  de- 
ficiency in  quality  or  strength  after  a  cylinder 
has  been  emptied  or  partly  emptied.  Therefore 
it  is  important  that  the  consumer  satisfy  him- 
self of  the  purity  of  the  ammonia  before  drawing 
off  the  contents  of  the  cylinder. 

EVAPORATION    TEST. 

Any  dealer  in  chemical  supplies  will  furnish 
an  8-ounce,  flat  bottom,  wide  neck,  Bohemian 
glass  boiling-  flask  (in  case  of  breakag-e  it  is  well 
to  have  several  of  these).  Fit  in  the  neck  a 
stopper  having-  a  ^-inch  vent  hole  punctured 
through  for  escape  of  the  gas.  Insert  in  this 
hole  a  short  g-lass  tube.  Procure  a  piece  of 
3/8-inch  iron  pipe,  threaded  at  one  end;  bend  the 
pipe  to  such  a  shape  that  the  threaded  end  can 
be  connected  with  the  cylinder  valve;  put  the 
wrench  on  the  valve  of  the  cylinder  and  open 
it  gently;  allow  a  little  of  the  ammonia  gas  to 
escape  at  first  in  order  to  purge  the  pipe  and 
valve,  then  draw  into  the  test  flask  from  2^  to 
4  ounces  of  the  liquid  ammonia.  When  this  is 
accomplished,  remove  the  test  flask  at  once, 
and  insert  in  the  neck  the  stopper  with  vent 
tube,  then  place  it  in  such  a  position  as  will 
allow  a  small  stream  of  water  to  flow  over  the 
sides  of  the  flask.  Under  these  conditions  the 
ammonia  will  boil  quickly  and  soon  evaporate. 
Any  residue  remaining  in  the  flask  indicates 
impurities.  Care  is  necessary  in  drawing  off 
the  sample,  as  a  very  little  moisture  in  the  test 
flask  or  in  the  pipe,  or  a  brief  exposure  to  the 
atmosphere,  will  at  once  affect  it. 


OF 


168 


MISCELLANEOUS   TABLES. 


COMPARISONS    OF    THERMOMETER    SCALES,    SHOWING 
RELATIVE  INDICATIONS  OF  THE  CELSIUS,  FAHREN- 
HEIT AND  REAUMUR  THERMOMETER  SCALES. 

In  the  United  States  and  England  the  Fahrenheit  scale  is  generally 
used;  in  France  and  in  all  scientific  investigations  and  treatises,  the 
Celsius  scale  is  uniformly  used;  and  in  Germany  the  Reaumur  scale  is 
the  one  generally  adopted. 


c. 

F. 

R. 

C. 

F. 

R. 

C. 

F. 

R. 

100° 

212.0° 

80.0° 

53° 

127.4° 

42.4° 

6 

42.8° 

4.<S° 

99 

210.2 

79.2 

5'i 

125.6 

41.6 

5          41.0 

4.0 

98 

208.4 

78.4 

51 

123.8 

40.8 

4 

39.2 

3.2 

97 

206.6 

77.6 

50 

122.0 

40.0 

3 

37.4 

2.4 

9i 

204.8 

76.8 

49 

120.2 

39.2 

2 

35.6 

lx.0 

93 

203.0 

76.0 

48 

118.4 

38.4 

1 

33.8 

O.H 

U 

201.2 

75.2 

47 

116.6 

37.6 

Zero 

32.0 

Zero 

93 

199.4 

74.4 

46 

114.8 

36.8 

1 

30.2 

0.8 

92 

197.6 

73.6 

45 

113.0 

36.0 

2 

28.4 

1.6 

91 

195.8 

72.8 

44 

111.2 

35.2 

3 

26.6 

2.4 

90 

194.0 

72.0 

43 

109.4 

34.4 

4 

24.8 

3.2 

89 

192.2 

71.2 

42 

107-6 

38.6 

5 

23.0 

4.0 

88 

190.4 

70.4 

41 

105.8 

32.8 

6 

21.2 

4.8 

87 

188.8 

69.6 

40 

104.0 

32.0 

7 

19.4 

5.6 

86 

186.8 

68.8 

39 

102.2 

31.2 

8 

17.6 

6.4 

85 

185.0 

68.0 

38 

100.4 

30.4 

9 

16.8 

7.2 

84 

183.2 

67.2 

37 

98.6 

29.6 

10 

14.0 

8.0 

b3 

181.4 

66.4 

36 

«6.8 

28.8 

11 

12  2 

8.8 

82 

179.6 

65.6 

36 

95.0 

28.0 

12 

10.4 

9.6 

81 

177.8 

64.8 

34 

93.2 

27.2 

13 

8.6 

10.4 

80 

176.0 

64.0 

33 

91.4 

26.4 

14 

6.8 

11.2 

79 

174.2 

63.2 

32 

89.6 

25.6 

15 

5.0 

12.0 

78 

172.4 

62.4 

31 

87.8 

24.8 

16 

3.2 

12.8 

77 

170.6 

61.6 

30 

86.0 

24.0 

17 

1.4 

13.6 

76 

168.8 

60.8 

29 

84.2 

23.2           18 

14.4 

75 

167.0 

60.0 

28 

82.4 

22.4           19 

2.2 

15.2 

74 

165.2 

59.2 

27 

80.6 

21.6           20 

4.0 

lfl.0 

73 

163.4 

58.4 

26 

78.8 

20.8     !      21 

5.8 

16.8 

72 

161.6 

57.6 

25 

77.0 

20.0     !      22 

7.6 

17.6 

71 

159.8 

56.8 

24 

75.2 

19.2           23 

9.4 

18.4 

70 

158.0 

56.0 

23 

73.4 

18.4    ||      24 

11.2 

19.2 

69 

156.2 

55.2 

22 

71.6 

17.6          25 

13.0 

20.0 

68 

154.4 

54.4 

21 

69.8 

16.8     !      26 

14.8 

20.8 

67 

152.6 

53.6 

20 

68.0 

16.0     i      27 

16  6 

21.6 

66 

ISO.  8 

52.8 

19 

66  2 

15.2    !       28 

18.4 

22.4 

65 

149.0 

52.0 

18 

64.4 

14.4     |      29 

20.2 

23.2 

64 

147.2 

51.2 

17 

62.6 

13.6 

30 

22.0 

24.0 

63 

146.4 

50.4 

16 

60.8 

12.8 

81 

23.8 

24.  8 

62 

143.6 

49.6 

15 

59.0 

12.0 

32 

25.6 

25.6 

61 

141.8 

48.8 

14 

57.2 

11.2    II      33 

27.4 

26.4 

60 

140.0 

48.0 

13 

.55.4 

10.4    i       34 

29.2 

27.2 

59 

138.2 

47.2 

12 

53.6 

9.6 

35 

31.0 

28.0 

58 

136.4 

46.4 

11 

51.8 

8.8 

36 

32.8 

28.8 

57 

134.3 

45.6    li      10 

50.0 

8.0 

37 

34.6 

29.6 

56 

132.8 

44.8             9 

48.2 

7.2 

38 

36.4 

30.4 

55 

131.0 

44.0 

8 

46.4 

6.4 

39 

38.2 

31.2 

54 

129.2 

43.2 

7 

44.6 

5.8 

40 

40.0 

32.0 

MISCELLANEOUS   TABLES. 


169 


MEAN    PRESSURE  OF    DIAGRAM  OF  AMMONIA 
COMPRESSOR. 

Reprinted  from  the  Catalogue  of  the  De  La  Vergne  Refrigerating 
Machine  Co. 


Oi  4^  CO 

Men  CD 

... 

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OO5CO        COO54^              to  <W 

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Condens 
pera 

Condense] 

m 

to  i—  '  i—  • 

O  O  O 

1            1      I      1               |l 

MM  tO             g  ^ 

enoen      oeno          S-™ 
ooo        ooo           pg. 

er  Tem- 
ture. 

•Pressure. 

4-  4-  *- 
O  CO  en 

—  .  _  — 

-4—  I  OO 

^.  ^  _       _  __  _ 
—  I  O5  en       4^  tO  M 

05 

L 

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bO  05  05 

oooo 

00004^ 

-4  CD  OO        4^  ^1  4^ 

4*  rfi.  C5        O  tO  O5 

'o 

CO 

—  —  ^' 

-4  CO  M 

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to  to  to 

Oi  en  4^        4^  4^  4^ 
h-  '  O  CD        —  4  Oi  CO 

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£2£ 

CO  O5  4*- 
0-40 

-4  Oi  M         CO  CO  CD 

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° 

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en  en  en 
'en  '4>  ^4 

CO  4^  -4 

en  en  en      en  45>.  *>. 
en  4^  to      o  -4  05 

—  4  M  4^        CO  CD  CO 
O  O5  tO        CO  O  4- 

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to 

—4 

OS  05  05 
—I  M  -4 

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to  to  •—  ' 

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CD  -4  en      co  o  oo 

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CD 

O5  O5  O5 
-4  OO  00 

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CD  o  en 

OO  tO  M 

O5  4i>  CD        tO  *>•  tO 
-4  O  —  4          Ol  O  CO 

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CO 

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4-4-4- 

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S050      gencg 

CD 

M 

%%Z 

to  oc  oc 

CO  M05 

§81^      ^SS 

° 

OC 

sbe§ 

00  05  *- 
4^  O5  tO 

—  i  O5  05      05  en  en 
t—1  oo  en      to  oo  os 

O5  O5  Oi          M  OO  M 
tO  tO  CO         O5  O5  M 

1 

2 

ajgg 

00  OO  -4 
CO  i—  00 

—4  —4  05      05  05  en 

en  to  oc      en  M  oo 

h-  ' 

r 

-j  CD  en 

0000  00 

O5  CO  Oi 

OO  CO  CD 

O5  tO  OO        t—  '  :•£•  Oi 
M  tO  M        4^-  O  4^ 

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p 

CO  CD  CD 
4-  CO  M 

OC  OO  GO 
OO  O5  tO 

—4  —4  »*4         O5  O5  O5 

CD  Oi  tO         OO  4^  O 

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M  OO  -4 

O5  OO  O         O  O  CD 
I—1  4^  GO         CO  OO  CD 

I 

00 

(12) 


170 


MISCELLANEOUS    TABLES. 


PROPERTIES  OF  SATURATED  STEAM, 


Total  pressure 
per 
square  inch. 

Temperature 
in  Fahrenheit 
degrees. 

Total  heat, 
in  Fahrenheit 
degrees,  from 
water  at  32°  F. 

Latent  heat, 
Fahrenheit 
degrees. 

Density,  or 
weight  of  one 
cubic  foot. 

Volume  of  one 
pound 
of  steam. 

Relative  vol- 
ume or  cubic 
feet  of  steam 
from  one  cubic 
foot  of  water. 

Lbs. 

Fahr. 

Fahr. 

Fahr. 

Lbs. 

Cubic  Feet 

Rel.  Vol. 

1 

102.1 

1112.5 

1042.9 

.0030 

330.36 

20600 

2 

126.3 

1119.7 

1025.8 

.0058 

172.08 

10730 

3 

141.6 

1124.6 

1015.0 

.0085 

117.52 

7327 

4 

153.1 

1128.1 

1006.8 

.0112 

89.62 

5589 

5 

162.3 

1130.9 

1000.3 

.0138 

72.66 

4530 

6 

170.2 

1133.3 

994.7 

.0168 

61.21 

3816 

7 

176.9 

1135.3 

990.0 

.0189 

52.94 

3301 

8 

182.9 

1137.2 

985.7 

.0214 

46.69 

2911 

9 

188.3 

1138.8 

981.9 

.0239 

41.79 

2606 

10 

193.3 

1140.3 

978.4 

.0264 

37.84 

2360 

11 

397.8 

1141.7 

975.2 

.0289 

34.63 

2157 

12 

202.0 

1143.0 

972.2 

.0314 

31.88 

1988 

18 

205.9 

1144.2 

969.4 

.0338 

29.57 

1844 

14 

209.6 

1145.3 

966.8 

.0362 

27.61 

1721 

14.7 

212.0 

1146.  1 

965.2 

.0380 

26.36 

1642 

15 

213.1 

1146.4 

964.3 

.0387 

25.85 

1611 

16 

216.3 

1147.4 

962.1 

.0411 

24.32 

1516 

J7 

219.6 

1148.3 

959.8 

.0435 

22.96 

1432 

18 

222.4 

1149.2 

957.7 

.0459 

21.78 

1357 

19 

225.8 

1150.1 

955.7 

.0483 

20.70 

1290 

20 

228.0 

1150.9 

952.8 

.0507 

19.72 

1229 

21 

230.6 

1151.7 

951.3 

.0531 

18.84 

1174 

22 

233.1 

1152.5 

949.9 

.0555 

18.03 

1123 

23 

235.5 

1153.2 

948.5 

.0580 

17.26 

1075 

24 

237.8 

1153.9 

946.9 

.0601 

16.64 

1036 

25 

240.1 

1154.6 

945.3 

.0625 

15.99 

996 

26 

242.3 

1155.3 

943.7 

.0650 

15.38 

958 

27 

244.4 

1155.8 

942.2 

.0673 

14.86 

926 

28 

246.4 

1158.4 

940.8 

.0696 

14.37 

895 

29 

248.4 

1157.1 

939.4 

.0719 

13.90 

866 

30 

250.4 

1157.8 

937.9 

.0743 

13.46 

838 

31 

252.2 

1158.4 

936.7 

.0766 

13.05 

813 

32 

254.1 

1158.9 

935.3 

.0789 

12.67 

789 

33 

255.9 

1159.6 

934.0 

.0812 

12.31 

767 

34 

257.6 

1160.0 

932.8 

.0835 

11.  U7 

74fl 

35 

259.3 

1160.5 

931.6 

.0858 

11.65 

726 

36 

260.9 

1161.0 

930.5 

.0881 

11.34 

707 

37 

262.6 

1161.5 

929.3 

.0905 

11.04 

688 

38 

264.2 

1162.0 

928.2 

.0929 

10.76 

671 

39 

265.8 

1162.5 

927.1 

.0952 

10.51 

655 

40 

267.3 

1162.9 

926.0 

.0974 

10.27 

640 

41 

268.7 

1163.4 

924.9 

.0996 

10.03 

625 

42 

270.2 

1163.8 

923.9 

.1020 

9.81 

611 

43 

271.6 

1164.2 

922.9 

.1042 

9.59 

698 

44 

273.0 

1164.6 

921.9 

.1065 

9.39 

585 

45 

274.4 

1165.1 

920.9 

.1089 

9.18 

572 

40 

275.8 

1165.5 

919.9 

.1111 

9.00 

561 

47 

277.1 

1165.9 

919.0 

.1133 

8.82 

550 

48 

278.4 

1166.3 

918.1 

.1156 

8.65 

539 

49 

279.7 

1166.7 

917.2 

.1179 

8.48 

529 

50 

281.0 

1167.1 

916.3 

.1202 

8.31 

518 

51 

282.3 

1167.5 

915.4 

.1224 

8.17 

509 

62 

283.5 

1167.9 

914.5 

.1246 

8.04 

500 

53 

284.7 

1168.3 

913.6 

.1269 

7.88 

491 

54 

285.9 

1168.6 

912.8 

.1291 

7.74 

482 

55 

287.1 

1169.0 

912.0 

.1314 

7.61 

474 

66 

288.2 

1169.3 

911.2 

.1336 

7.48 

466 

MISCELLANKOUS    TABLES. 


171 


PROPERTIES    OF  SATURATED    STEAM.— CONT. 


Total  pressure 
per 
square  inch,  j 

Temperature 
in  Fahrenheit 
degrees. 

Total  heat, 
in  Fahrenheit 
degrees,  from 
water  at  32°  F. 

Latent  heat, 
Fahrenheit 
degrees. 

i 
Density,  or 
weight  of  one 
cubic  foot. 

Volume  of  one 
pound 
of  steam. 

Relative  vol- 
ume or  cubic 
feet  of  steam 
from  one  cubic 
foot  of  water. 

Lbs. 

Fahr. 

Fahr. 

Fahr. 

Lbs. 

Cubic  Feet 

Rel.  Vol. 

57 

289.3 

1169.7 

910.4 

.1364 

7.38 

458 

68 

290.4 

1170.0 

909.6 

.1380 

7.24 

451 

59 

291.6 

1170.4 

908.8 

.1403 

7.12 

444 

60 

292.7 

1170.7 

908.0 

.1425 

7.01 

437 

61 

293.8 

1171.1 

907.2 

.1447 

6.90 

430 

62 

204.3 

1171.4 

906.4 

.1469 

6.81 

424 

63 

295.9 

1171.7 

905.6 

.1493 

6.70 

417 

64 

296.9 

1172.0 

904.9 

.1516 

6.60 

411 

65 

298.0 

1172.3 

904.2 

.1538 

6.49 

405  - 

66 

299.0 

1172.6 

903.5 

.1560 

6.41 

399 

67 

300.0 

1172.9 

902.8 

.1583 

6.32 

393 

68 

300.9 

1173.2 

902.1 

.1605 

6.23 

388 

69 

301.9 

1173.5 

901.4 

.1627 

6.15 

383 

70 

302.9 

1173.8 

900.8 

.1648 

6.07 

378 

71 

303.9 

1174.1 

900.3 

.1670 

5.99 

373 

72 

304.8 

1174.3 

899.6 

.1692 

5.91 

368 

73 

305.7 

1174.6 

898.9 

.1714 

5.83 

363 

74 

306.6 

1174.9 

898.2 

.1736 

5.75 

359 

75 

307.5 

1175.2 

897.5 

.1759 

5.68 

353 

76 

308.4 

1175.4 

896.8 

.1782 

5.61 

349 

77 

309.3 

1175.7 

896.1 

.1804 

5.54 

345 

78 

310.2 

1176.0 

895.5 

.1826 

5.48 

341 

79 

311.1 

1176.3 

894.9 

.1848 

5.41 

337 

80 

312.0 

1176.5 

894.3 

.1869 

5.35 

333 

81 

312.8 

1176.8 

893.7 

.1891 

5.29 

329 

82 

313.6 

1177.1 

893.1 

.1913 

5.23 

325 

83 

314.5 

1177.4 

892.5 

.1935 

5.17 

321 

84 

315.3 

1177.6 

892.0 

.1957 

5.11 

318 

85 

316.1 

1177.9 

891.4 

.1980 

5.05 

314 

86 

316.9 

1178.1 

890.8 

.2002 

5.00 

311 

87 

317.8 

1178.4 

890.2 

.2024 

4.94 

308 

88 

318.6 

1178.6 

889.6 

.2044 

4.89 

305 

89 

319.4 

1178.9 

889.0 

.2067 

4.84 

301 

90 

320.2 

1179.1 

888.5 

.2089 

4.79 

298 

91 

321.0 

1179.3 

887.9 

.2111 

4.74 

295 

92 

321.7 

1179.6 

887.3 

.2133 

4.69 

292 

93 

322.5 

1179.8 

886.8 

.2155 

4.64 

289 

94 

323.3 

1180.0 

886  3 

.2176 

4.60 

288 

95 

324.1 

1180.3 

886  8 

.2198 

4.56 

283 

96 

324.8 

1180.5 

885.2 

.2219 

4.51 

281 

97 

325.6 

1180.8 

884.6 

.2241 

4.46 

278 

98 

326.3 

1181.0 

884.1 

.2263 

4.42 

275 

99 

327.1 

1181.2 

883.6 

.2285 

4.37 

272 

100 

327.9 

1181.4 

883  1 

.2307 

4.33 

270 

101 

328.5 

1181.6 

882.6 

.2329 

4.29 

267 

102 

329.1 

1181.8 

882  1 

.2351 

4.25 

265 

103 

329.9 

1182.0 

881.6 

.2373 

4.21 

262 

104 

330.6 

1182.2 

881  1 

.2393 

4.18 

2«0 

105 

331.3 

1182.4 

880.7 

.2414  !   4.14 

287 

106 

331.9 

1182.6 

880  2 

.2435  '   4.11 

255 

107 

332.6 

1182.8 

879.7 

.2456  j   4.07 

253 

108 

333.3 

1183.0 

879.2 

.2477  1   4.04 

251 

109 

334.0 

1183.3 

878  7 

.2499 

4.00 

249 

110 

334.6 

1183.5 

878.3 

.2521 

3.97 

?47 

111 

335.3 

1183.7 

877.8 

.2543 

3.93 

246 

112 

336.0 

1183.9 

877.3 

.2564 

3.90 

243 

113 

336.  7 

1184.1 

876.8 

.2586 

3.86 

241 

172 


MISCELLANEOUS    TABLES. 


PROPERTIES    OF  SATURATED    STEAM.— CONT. 


Total  pressure]! 
per 
square  inch.  | 

Temperature 
in  Fahrenheit 
degrees. 

Total  heat, 
in  Fahrenheit 
degrees,  from 
water  at  32°  F. 

Latent  heat, 
Fahrenheit 
degrees. 

1 
Density,  or 
weight  of  one 
cubic  foot. 

Volume  of  one 
pound 
of  steam. 

mi 
Kl! 

Illll 

Lbs. 

Fahr. 

Fahr. 

Fahr. 

Lbs. 

Cubic  Fest 

Rel.  Vol. 

114 

337.4 

1184.3 

876.3 

.2607 

3.&3 

239 

115 

338.0 

1184.5 

875.9 

.2628 

3.80 

237 

116 

338.6 

1184.7 

875.5 

.2649 

i.77 

2*5 

117 

339.3 

1164.9 

875.0 

.2652 

3.74 

2:w 

118 

339.9 

1185.1 

874.5 

.2674 

3.71 

231 

119 

340.5 

1185.3 

874.1 

.2696 

3.68 

229 

120 

341.1 

1185.4 

873.7 

.2738 

3.65 

227 

121 

341.8 

1185.6 

873.2 

.2759 

3.62 

225 

122 

342  4 

1185.8 

872.8 

.2780 

3.59 

224 

123 

343.0 

1186.0 

872.3 

.2801 

3.56 

2^2 

124 

343.6 

1186.2 

871.9 

.2822 

3.54 

221 

125 

344.2 

1186.4 

871.5 

.2845 

3.51 

219 

126 

344.8 

1186.6 

871.1 

.2867 

3.49 

-  I  ' 

127 

345.4 

1186.8 

870.7 

.2889 

3.46 

215 

128 

346.0 

1186.9 

870.2 

.2911 

3.44 

214 

129 

346.6 

1187.1 

869.8 

.2933 

3.41 

212 

130 

347.2 

1187.3 

8*0.4 

.2955 

3.38 

211 

131 

347.8 

1187.5 

869.0 

.2977 

3.35 

209 

132 

348.3 

1187.6 

868.6 

.2999 

3.33 

20S 

133 

348.9 

1187.8 

868.2 

.3020 

3.31 

206 

134 

349.5 

1188.0 

867.8 

.3040 

3.29 

205 

135 

350.1 

1188.2 

867.4 

.3060 

3.27 

203 

136 

K50.6 

1188.3 

867.0 

.3080 

3.25 

202 

137 

351.2 

1188.5 

866.6 

.3101 

3.22 

200 

138 

351.8 

1188.7 

866.2 

.3121 

3.20 

199 

139 

352.4 

1188.9 

865.8 

.3142 

3.18 

198 

140 

352.9 

1189.0 

865.4 

.3162 

3.16 

197 

141 

353.5 

1189.2 

865.0 

.3184 

3.14 

195 

142 

364.0 

1189.4 

864.6 

.3206 

3.12 

194 

143 

354.5 

1189.6 

864.2 

.3228 

3.10 

193 

144 

355.0 

1189.7 

863.9 

.3250 

3  08 

102 

145 

355.6 

1189.9 

863.5 

.3273 

3.06 

190 

146 

356.1 

1190.0 

863.1 

.3294 

3.04 

189 

147 

356.7 

1190.2 

862.7 

.3315 

3.02 

18.H 

148 

35T.2 

1190.3 

862.3 

.3H36 

3.00 

187 

149 

357.8 

1190.5 

861.9 

.3357 

2.98 

186 

150 

358.3 

1190  7 

861.5 

.3377 

2.96 

184 

155 

361.0 

1191.5 

859.7 

.3484 

2.87 

179 

160 

363.4 

1192.2 

857  9 

.3590 

2.79 

174 

165 

366.0 

1192.9 

856.2 

.3695 

2.71 

169 

170 

368.2 

1193.7 

854.5 

.3798 

2.63 

164 

175 

370.8 

1194.4 

852.9 

.3899 

2.56 

159 

180 

372.9 

1195.1 

851.3 

.4009 

2.49 

155 

185 

375.3 

1195.8 

849.6 

.4117 

2.43 

151 

190 

377.5 

1196.5 

848.0 

.4222 

8.37 

14S 

195 

379.7 

1197.2 

846.5 

.4327 

2.31 

144 

200 

381.7 

1197.8 

845.0 

.4431 

2.26 

141 

210 

386.0 

1199.1 

841.9 

.4634 

2.16 

135 

220 

389.9 

1200.3 

839.2 

.4842 

2.06 

129 

230 

393.8 

1201.5 

836.4 

.6052 

.98 

123 

240 

397.5 

1202.6 

833.  8 

.5248 

.90 

119 

250 

401.1 

1203.7 

831.2 

.5464 

.83 

114 

260 

404.5 

1204.8 

828.8 

.56K9 

.76 

110 

270 

407.9 

1205.8 

826.4 

.5868 

.70 

108 

280 

411.2 

1206.8 

824.1 

.6081 

.64 

102 

290 

414.4 

1207.8 

821.8 

.6273 

.59 

99 

300 

417.5 

1208.7 

819.6 

.6486 

.54 

93 

MISCELLANEOUS   TABLES. 


173 


MEAN  EFFECTIVE  PRESSURE  OF  DIAGRAM 
OF  STEAM  CYLINDER. 


$553313  BaSSSRStS 


sis* 


The  M.  E.  P.  for  any  initial  pressure  not  given  in  the  table  can  be  found 
by  multiplying-  the  (absolute)  given  pressure  by  the  M.E.  P.  per  pound 
of  initial,  as  given  in  the  third  horizontal  line  of  the  table. 


174 


MISCELLANEOUS   TABLES. 


HEAD  OF  WATER  AND  EQUIVALENT  PRESS- 
URE IN  POUNDS  PER  SQUARE  INCH. 


II 

£ 

•d  .5 
rti; 

w.s 

£ 

'C4J 

& 

£ 

M.S 

1 

Id' 
&* 

£ 

1 

0.43 

~41 

17.75 

81 

35.08 

121 

52.41 

161 

69.74 

2 

0.86 

42 

18.19 

82 

35.52 

122 

52.84 

162 

70.17 

3 

1.30 

43 

18.62 

83 

35.95 

>123 

53.28 

163 

70.61 

4 

1.73 

44 

19.05 

84 

36.39 

124 

53.71 

164 

71.04 

5 

2.16 

45 

19.49 

85 

36.82 

125 

54.15 

165 

71.47 

6 

2.59 

46 

19.92 

86 

37.25 

126 

54.58 

166 

71.91 

7 

3.03 

47 

20.35 

87 

37.68 

:127 

55.01 

167 

72.34 

8 

3.46 

48 

20.79 

88 

38.12 

128 

55.44 

168 

72.77 

9 

3.89 

\  49 

21.22; 

89 

38.55;  129 

55.88 

169 

73.20 

10 

4.33 

50 

21.65 

90 

39.98 

130 

56.31 

170 

73.64 

11 

4.76 

51 

22.09 

91 

39.42 

131 

56.74 

171 

74.07 

12 

5.20 

52 

22.52 

92 

39.85 

132 

57.18 

172 

74.50 

13 

5.63 

53 

22.95 

93 

40.28 

133 

57.61 

173 

74.94 

14 

6.06 

54 

23.39 

94 

40.72 

134 

58.04 

174 

75.37 

15 

6.49 

55 

23.82 

95 

41.15 

135 

58.48 

175 

75.80 

16 

6.93 

56 

24.26 

96 

41.58 

136 

58.91 

176 

76.23 

17 

7.36 

57 

24.69 

97 

42.01 

137 

59.34 

177 

76.67 

18 

7.79 

58 

25.12 

98 

42.45 

138 

59.77 

178 

77.10 

19 

8.22 

59 

25.55' 

99 

42.88 

139 

60.21 

179 

77.53 

20 

8.66 

60 

25.99 

100 

43.31 

,140 

60.64 

180 

77.97 

21 

9.09 

61 

26.42: 

101 

43.75 

141 

61.07 

181 

78.40 

22 

9.53 

62 

26.85 

102 

44.18 

142 

61.51 

182 

78.84 

23 

9.96 

63 

27.29 

103 

44.61 

143 

61.94 

183 

79.27 

24 

10.39 

64 

27.72 

104 

45.05 

144 

62.37 

184 

79.70 

25 

10.82 

65 

28.151 

105 

45.48 

145 

62.81 

185 

80.14 

26 

11.26 

66 

28.58 

106 

45.91 

;146 

63.24 

186 

80.57 

27 

11.69 

67 

29.02 

107 

46.34 

147 

63.67 

187 

81.00 

28 

12.12 

68 

29.45 

108 

46.78 

148 

64.10 

188 

81.43 

29 

12.55 

69 

29.88 

109 

47.21 

149 

64.54 

189 

81.87 

30 

12.99 

70 

30.32 

110 

47.64 

150 

64.97 

190 

82.30 

31 

13.42 

71 

30.75 

111 

48.08 

151 

65.49 

191 

82.77 

32 

13.86 

72 

31.18 

112 

48.51 

152 

65.84 

192 

83.13 

33 

14.29 

73 

31.62llll3 

48.94 

153 

66.27 

193 

83.60 

34 

14.72 

74 

32.05 

114 

49.38 

154 

66.70 

194 

84.03 

35 

15.16 

75 

32.48 

115 

49.81 

155 

67.14 

195 

84.47 

36 

15.59 

76 

32.92 

116 

50.24 

156 

67.57 

196 

84.90 

37 

16.02 

77 

33.35 

117 

50.68 

157 

68.00 

197 

85.33 

38 

16.45 

78 

33.78 

118 

51.11 

158 

68.43 

198 

85.76 

39 

16.89 

79 

34.21 

119 

51.54 

|159 

68.87 

199 

86.20 

40 

17.32 

80 

34.65J  120 

51.98 

1160 

69.31 

200 

86.63 

MISCELLANEOUS   TABLES. 


175 


TABLE  SHOWING  PROPERTIES  OF  SOLUTION 
OF  SALT. 

(Chloride  of  Sodium.) 


Percentage 
of  Salt  by  M 
Weig-ht. 

Pounds  of 
Salt  per 
Gallon  of  w 
Solution. 

3 

C  !-> 
"|? 

Q$  rt 

Weight  per 
Gallon  at  ^ 
39°  P.-4°  C. 

5 

a«o 

•|£°T  • 

*!£. 

6 

y 

£  -^ 
J)  o) 

W 

Freezing- 
Point,  -a 
Fahrenheit. 

1 

9 

0.084 
0  169 

4 
g 

8.40 
8  46 

1.007 
1  015 

0.992 

30.5 
29  3 

2  5 

0  212 

10 

8  50 

1  019 

28  6 

3 

0  256 

12 

8  53 

1  023 

27  8 

3  5 

0  300 

14 

8  56 

1  026 

27  1 

4 

0  344 

16 

8  59 

1  030 

26  6 

5 

0.433 

20 

8.65 

1.037 

0.960 

25.2 

6 

0  523 

24 

8  72 

1  045 

23  9 

7 

0  617 

28 

8  78 

1  053 

22  5 

8 

0  708 

32 

8  85 

1  061 

21  2 

9 
10 

0.802 
0.897 

36 
40 

8.91 
8.97 

1.068 
1.076 

6  '.892 

19.9 
18.7 

12 
15 
20 

1.092 

1.389 
1.928 

48 
60 
80 

9.10 
9.26 
9.64 

1.091 
1.115 
1.155 

6  '.855 
0.829 

16.0 
12.2 
6.1 

24 

2  376 

96 

9  90 

1  187 

1  2 

25 
26 
29 

2.488 
2.610 

100 

9.97 
10.04 

1.196 
1.204 

0.783 

.5 
—1.1 

—4.7 

To  determine  the  weig-ht  of  one  cubic  foot  of  brine,  multiply  the  values 
given  in  column  4  by  7.48. 

To  determine  the  weig-ht  of  salt  to  one  cubic  foot  of  brine,  multiply  the 
values  given  in  column  2  by  7.48. 


PROPERTIES  OF  SOLUTION  OF  CHLORIDE 
OF  CALCIUM. 


Percentage 
by  Weight. 

Specific 
Heat. 

Spec.  Grav. 
at  60°  F. 

Freezing 
Point, 
Degrees  F. 

Freezing  Point, 
Deg.  Cels. 

1 

0.996 

1.009 

31 

—  0.5 

5 

0.964 

1.043 

27.5 

—  2.5 

10 

0.896 

1.087 

22 

—  5.6 

15 

0.860 

1.134 

15 

—  9.6 

20 

0.834 

1.182 

-  1.5 

—14.8 

25 

0.790 

1.234 

—21.8 

—22.1 

176 


MISCELLANEOUS    TABLES. 


DIAMETERS,  AREAS  AND  CIRCUMFERENCES 
OF  CIRCLES. 


Diam.  | 
Inches. 

Circumf. 
Inches. 

I- 

<s 

ll 

E^  ao 
1» 

^x; 

i* 

if 

a  "> 
B  <u 

3£Z 

«^    ' 
o> 

QC 

b  G 
bw 

*& 

QC 

£S 
o 

<ti 

1 

3.14159 

0.78540 

4 

12.5664 

12  566 

8 

25  1327 

50.265 

,  jtj 

3.3379.4 

0.88664' 

1*0 

12.7627 

12.962 

'/8 

25  5224 

;>1.849 

1  '4 

3.53429 

0.99402 

1 

12.9591 

13.364 

*4 

2f>.  91  8  1 

53.456 

ft 

3.73064 

.1076 

,3* 

13.1554 

13.772 

% 

26.3108 

56.0b8 

3.92699 

.2272 

k 

13.3518. 

14.186 

l/2 

26.7035 

56.746 

isl 

4.12334 

.3530 

i5f, 

13.5481 

14.607 

X 

27.0962 

58.426 

x 

4.31969 

.4849 

% 

13.7445 

15.033 

% 

27.  4889 

60.132 

1  6 

4.51604 

.6230 

J76 

13.9408 

15.466 

27.  f  816 

61.862 

Va 

4.71239 

.7671 

K 

14.1372 

15.904 

9 

28.2743 

63.617 

,"6 

4.90874 

.9175 

ft 

14.3335 

16.349 

H 

28.  6670 

65.397 

% 

5.10509 

2.0739 

% 

14.5299 

16.1-00 

H 

29.0597 

67.201 

U 

5.30144 

2.236C 

{I 

14.7^62 

17.257 

% 

29.4624 

69.029 

a4 

5.49779 

2.4053 

£ 

14.  9226 

17.721 

% 

29.8451 

70.882 

1  3 

5.69414 

2.5802 

n 

15.1189 

18.190 

% 

30.2378 

72.760 

X 

5.89049 

2.7612 

% 

15.3153 

18.665 

% 

30.6305 

74.662 

18 

6.08684 

2.9483 

\i 

15.5116 

19.147 

% 

31.0232 

76.689 

2 

6.2*319 

3.1416 

5 

15.70PO 

19  635 

10 

31  4159 

78.540 

,!B 

6.47953 

3.3410 

A 

15.9043 

20.129 

y± 

32.2013 

82.516 

M 

6.67588 

3.54«6 

% 

16.1007 

20.629 

Yz 

32.9*67 

86.590 

ft 

6.87223 

3.7583 

A. 

16.2970 

21.135 

\ 

33.7721 

90.763 

J4 

7.06858 

3.9761 

H 

16.4934 

21.648 

11 

3-4.5575 

95.033 

156 

7.26493 

4.2000 

1*8 

16.6897 

22.166 

1A 

35.3429 

99.402 

% 

7.46128 

4.4301 

% 

16.8861 

22.6H1 

£ 

36.1283 

103.87 

7.65763 

4.6664 

I7* 

17.0824 

23.221 

K 

36.9137 

108.43 

*/2 

7.85398 

4.9087 

K 

17.2788 

23.758 

12 

37.6991 

113.10 

198 

8.05033 

5.1572 

:!98 

17.4751 

24.301 

y* 

38.4845 

117.86 

H 

8.24668 

5.4119 

% 

17.6715 

24.850 

% 

39.2699 

122.72 

H 

8.44303 

5,6727 

\l 

17.8678 

25.406 

% 

40.0563 

127.68 

\ 

8.63938 

5.9396 

X 

18.0642 

25  967 

13 

40.8407 

132.73 

1* 

8.83573 

6.2126 

tf 

18.2605 

26.535 

H 

il.6261 

137.89 

% 

9.03208 

6.4918 

% 

18.4569 

27  .'109 

V4 

42.4115 

143.14 

11 

9.22843 

6.7771 

18 

18.6532 

27.688 

M 

43.1969 

148.49 

3 

9.424:8 

7.0686 

6 

18.8496 

28.274 

14 

43.9823 

153.94 

•iVs 

9.62113 

7.3662 

H 

19.2423 

29.465 

y\ 

44.7671 

159.48 

H- 

9.81748 

7.6699 

H 

19.6350 

30.680 

Vz 

45.5531 

165.13 

•>36 

10.0138 

7.9798 

% 

20.0277 

31.919 

X 

46.3385 

170.87 

H 

10.2102 

8.2958 

1A' 

20.4204 

33.183 

15 

47.1239 

176.71 

IB 

10.4065 

8.6179 

% 

20.8131 

34.472 

H 

47.9'093 

182.65 

%' 

10.P029 

8.9462 

% 

21.2058 

35.785 

54 

48.6947 

188.69 

1?R 

10.7992 

9.2806 

% 

21.5984 

37.122 

49.48D1 

194.83 

H 

10.9956 

9.6211 

1 

21.9911 

38.485 

16 

50.2655 

201.06 

ft" 

11.1919 

9.9678 

y* 

22.3838 

39.871 

y* 

51.0509 

207.39 

« 

11.3883 

10.321 

M 

22.7765 

41.282 

H 

51.8363 

213.82 

Ji 

11.5846 

10.680 

% 

23.1692 

42.718 

\ 

52.6217 

220.35 

% 

11.7810 

11.045 

l/2 

23.5619 

44.179 

17 

53.4071 

226.98 

ia 

I  <> 

11.9772 

11.416 

5jj 

23.9546 

45.664 

k 

54.1925 

233.71 

•fe 

12.1737 

11.793 

% 

24.3473 

47.173 

l/2 

54.9779 

240.53 

.18 

12.3700 

12.177 

7/9 

24.7400 

48.707 

#5.7(533 

247.45 

MISCELLANEOUS   TABLES. 


177 


DIAMETERS,  AREAS  AND  CIRCUMFERENCES 
OF  CIRCLES.— CONTINUED. 


a| 
.2-3 

Qfl 

Circumt". 
Inches. 

•  1 

ll 

Diam. 
Inches. 

Circumf. 
Inches. 

•>  . 

Diam.  I 
Inches. 

Circumf. 
Inches. 

s 

18 

56.5487 

254.47 

J3 

100  531 

804  25 

46 

144.513 

1661.9 

57  3341 

261.59 

/4 

101.316 

816.86 

/4 

145.21)9 

1680.0 

H 

58.1195 

268  80 

Yz 

102.102 

829.58 

Yz 

146  U84 

1698.2 

X 

58.9049 

276.12 

% 

102  887 

842.39 

34 

146  86!) 

1716  5 

19 

59.6903 

283.53 

33 

103  673 

855.30 

47'  ' 

147  65.' 

1734  9 

60  47.37 

291.04 

104.458 

868.31 

/4 

148.440 

1753.5 

Yz 

61.2611 

208.65 

Yz 

105  243 

881.41 

Yz 

149.226 

1772  J 

% 

62.0465 

306'.  35 

?4 

106.029 

894.62 

% 

150.011 

1790.8 

20 

62.8319 

314.16 

34 

106.814 

907.92 

48 

150.796 

1809  6 

63.6173 

322.06 

107.600 

921.32 

151.582 

1828.5 

Yz 

64.4036 

330.06 

Yz 

108.385 

934.82 

Yz 

152.367 

1847.5 

"X 

66.1830 

338.16 

% 

109.170 

948.42 

% 

153.153 

1866.5 

21 

65.9734 

346.36 

35' 

109.956 

962.11 

49 

153.938 

1885.7 

66.7588 

354.66 

X 

110.741 

975.91 

Y\ 

154.723 

1905.0 

V» 

67.5442 

363.05 

Yz 

111.627 

989.  80 

Yz 

155.509 

1924.2 

X 

68.3398 

371.54 

112.312 

1003.8 

$4. 

156.294 

1943.9 

69.1150 

380.13 

36  4 

113.097 

1017.9  . 

50 

157.080 

1963.5 

1 

69.9004 

388.82 

\2 

113.883 

1032.1 

\i 

157.865 

1983.2 

% 

70.6858 

397.61 

•% 

114.668 

1046.3 

Yz 

158.650 

2003.0 

^ 

71  4712 

406.49 

% 

115.454 

1060.7 

159.436 

2022.8 

23 

72.2566 

415.48 

3? 

116.239 

1075.2 

51  4 

160.221 

2042.8 

73.0420 

424.56 

Y±     117.024 

1089.8 

161.007 

2062.9 

/4 

73.8274 

433.74 

M 

117.810 

1104.5 

Yz 

161.792 

2083.1 

24 

74.6128 

443.01 

X 

118.596 

1119.2 

% 

162  577 

2103.3 

24 

75.3982 

452.39 

38 

119.381 

1134.1 

52 

163.363 

2123.7 

76.1836 

461.86 

X 

120.166 

1149.1 

164.148 

2144.2 

^2 

76.9690 

471.44 

120.951 

1164.2 

~"  Yz 

164.934 

2164.8 

Jj£ 

77.7544 

481.11 

% 

121.737 

1179.3 

% 

165.719 

2185.4 

25 

78.5398 

490.87 

39 

122.522 

1194.6 

53 

166.504 

2206.2 

\,' 

79.3252 

500.74 

123.308 

1310.0 

J4 

167.290 

2227.0 

Yt 

80.1106 

510.71 

Yz 

124.093 

1225.4 

Yz 

168.075 

2248.0 

80.8960 

620.77 

124.878 

1241.0 

94 

168.861 

2269.1 

26^ 

81.6814 

630.93 

404 

125.664 

1266.6 

54 

169..  646 

2290.3 

82.4668 

541.  19 

126.449 

1272.4 

170.431 

2311.5 

i^ 

83.2522 

551.55 

y* 

127.235 

1288.2 

Yz 

171.217 

2332.8 

2  ' 

84.0376 

562.00 

128.020 

1304.2 

172.002 

2354.3 

27* 

84.8230 

572.66 

414 

128.805 

1320.3 

55^ 

172.788 

2376.8 

85.6084 

583.21 

129.591 

1336.4 

X 

173.573 

2397.5 

Yt 

86.3938 

593.96 

X 

130.376 

1352.7 

174.358 

2419.2 

94 

87.1792 

604.81 

94 

131.161 

1369.0 

94 

175.144 

2441.1 

28 

87.9646 

615.75 

42 

131.947 

1385.4 

56 

175.929 

2463.0 

J4 

88.7500 

626.80 

J4 

132.  732 

1402.0 

176.715 

2485.0 

!4 

89.5354 

637.94 

133.518 

1418.6 

4 

177.500 

2607.2 

a^ 

90.3208 

649.18 

24 

134.303 

1436.4 

178.285 

2529.4 

29 

91.1062 

660.52 

43- 

135.088 

1452.2 

57  4 

179.071 

2551.8 

/4 

91.8916 

671.96 

i  • 

135.874- 

1469.1 

/4 

179.856 

2574.2 

Yz 

92.67r<0 

683.49 

Y« 

136.659 

1486.2 

y* 

180.642 

2596.7 

% 

93.4624 

695.13 

X 

137  445 

1503.3 

24 

181.427 

2619.4 

30 

94.2478 

706.86 

44 

138.230 

1620.5 

58 

182.212 

2642.1 

95.0332 

718.69 

139.015 

1537.9 

i^ 

182.998 

2664.9 

8 

95.8186 

730.62 

Yz 

139.801 

1555.3 

<y 

183.783 

2687.8 

96.6040 

742.64 

94 

140.586 

1572.8 

% 

184.569 

2710.9 

31.4 

97.3894 

754.77 

45 

141.372 

1590.4 

59 

1&5.354 

2734.0 

98.1748 

766.99 

X 

142.157 

1608.2 

186.139 

2757.2 

% 

98.9602 

779.31 

Yz 

142.942 

1626.0 

Yz 

186.925 

2780.5 

% 

99.7466 

791.73 

143.728 

1643.9 

% 

187.  7JO 

2803.9 

178 


MISCELLANEOUS    TABLES. 


DIAMETERS,  AREAS  AND  CIRCUMFERENCES 
OF  CIRCLES.— CONTINUED. 


rig 

«*H      • 

g  en 

•  f3 

at 

ii 

d£ 

S£ 

•J 

§1 

»S 

3,a 
££ 
0M 

$?• 

!•§ 

QC 

XA 
^d 

o" 

ll 

d.a 
o  o 
^a 
Ow 

«M 

60 

188.496 

2827.4 

74 

232.478 

4300.8 

88 

276.460 

6082.1 

% 

189.281 

2851.0 

k. 

233.263 

4329.9 

/4 

277.246 

6116.7 

2 

190.066 

2874.8 

234.049 

4359.2 

Y~ 

278.031 

6151.4 

190.852 

2898.6 

5 

234.834 

4388.5 

% 

278.816 

6186.2 

61* 

191.637 

2922.5 

75 

235.619 

4417.9 

89 

279.602 

6221.1 

192.423 

2946.5  ! 

236.405 

4447.4 

280.387 

6256.1 

'Yz 

193.208 

2970.6 

y2 

237.190 

4477,0 

y?. 

281.173 

6291.2 

% 

193.993 

2994:8  ! 

% 

237.976 

4506.7 

% 

281.958 

6326.4 

®i 

194.779 

3019.1 

76 

238.761 

4536.5 

90 

282.743 

6361.7 

195.564 

3043.5 

y± 

239.546 

4566.4 

Ji 

283.629 

6397.1 

Vt 

196.35JU 

3068.0 

Yz 

240.332 

4596.3 

Yt 

284.314 

6432.6 

197.135 

3092.6 

241.117 

4626.4 

285.100 

6468.2 

63* 

197.920 

3117.2 

77 

241.903 

4656.6 

91* 

288.885 

6503.9 

198.706 

3142.0 

/4 

242.  688 

4686.9 

/4 

286.670 

6539.7 

Yz 

199.491 

3166,9 

Yz 

243.473 

4717.3 

287.466 

6575  5 

200.277 

3191.9 

%. 

244.259 

4747.8 

2i 

288.241 

6611.5 

644 

201.062 

3217.0 

78 

245.044 

4778.4 

92 

289.027 

6647.6 

201.847 

3242.2 

245.830 

4809.0 

289.812 

6683.8 

Yz 

202.633 

3267.5 

Yz 

246.615 

4839.8 

Yz 

290.597 

6720.1 

% 

203.418 

3292.8 

3L' 

247.400 

4870.7 

M 

291.383 

6766.4 

65 

204.204 

3318.? 

79 

248.186 

4901.7 

93 

292.168 

6792.9 

204.989 

3343.9 

y*. 

248.971 

4932.7 

/4 

292.954 

6829.  5 

Yz 

205.774 

3369.6 

y* 

249.757 

4963.9 

Yz 

293.739 

6866.1 

% 

206.560 

3395.3 

250.542 

4995.2 

% 

294.524 

6902.9 

66 

207.345 

3421.2 

80*. 

261.327 

5026.5 

94 

295.310 

6939.8 

/4 

208.131 

3447.2 

i> 

252.113 

5058.0 

!/• 

296.095 

6976.7 

•V6 

208.916 

3473T2 

H 

252.898 

5089.6 

Yz 

296.881 

7013.8 

9£ 

209.701 

3499.4 

253.684 

5121.2 

% 

297.666 

7051.0 

67 

210.487 

3526." 

81* 

254.469 

5153.0 

95 

298.451 

7088.2 

/4 

211.272 

3552.0 

H 

255.254 

5184.9 

14 

299.237 

7125.6 

i^ 

212.058 

3578.5 

Yz 

256.040 

5216.8 

i/ 

300.022 

7163.0 

M 

212.843 

3605.0 

256.825 

5248.9 

If 

300.807 

7200.6 

68' 

213.628 

3631.7 

82* 

257.611 

5281.0 

96 

301.593 

7238.2 

/4 

214.414 

3658.4 

/4 

258.396 

5313.3 

\A 

302.378 

7276.0 

14 

215.199 

3685.3 

Yz 

259.181 

5345.6 

Yz 

303.164 

7313.8 

3i 

215.984 

3712.2 

% 

259.967 

5378.1 

303.949 

7361.8 

69 

216.770 

3739.3 

83 

260.752 

5410.6 

97  /4 

304.734 

7389.8 

K 

217.555 

3766.4 

y± 

261.538 

5443.3 

/4 

305.520 

7428.0 

H 

2I8.-341 

3793-7 

Yz 

262.323 

5^76  0 

Yz 

306.305 

7466:2 

219.126 

3821.0 

%. 

263.108 

5508.8 

% 

307.091 

7504.5 

70* 

219.911 

3848.  5 

84    . 

263.894 

5541.8 

98 

307.876 

7543.0 

/£ 

220.697 

3876.0 

264.679 

5574.8 

H 

308.661 

7581:5 

Yz 

221.482 

3903.6 

y* 

265.465 

5607.9 

309.447 

7620.1 

% 

222.268 

3931.4 

% 

266.260 

5641.2 

% 

310-232 

7658.9 

71 

223.053 

3959.2 

85 

267.035 

5674.5 

99 

311.018 

7697.7 

"/£ 

223.838 

3987.1 

i/ 

267.821 

5707.9 

M 

311.803 

7736.6 

Va 

224.624 

4015.2 

Yz 

268.606 

5741.5 

Yz 

312.588 

7775.6 

% 

225.  409 

4043.3 

% 

269.392 

5775.1 

% 

313.374 

7814.8 

72 

226.195 

4011.5 

86 

270.177 

5808.8 

100 

314.159 

7854  0 

/i 

226.980 

4099.8 

/4 

270.  962 

5842.6 

y2 

227.765 

4128.2 

Yz 

271.748 

5876.5 

3£ 

228.551 

4156.8 

% 

272.533 

5910.6 

"•"S 

229.336 

4185.4 

87 

273.319 

5944.7 

Ji 

230.122 

4214.1 

274.104 

5978.9 

i4 

230.907 

4242.9 

Yz 

274.889 

6013.2 

231.692 

4271.8 

275.675 

r>047.fi 

MISCELLANEOUS   TABLES.  179 

TABLE  OF  PISTON  SPEEDS.— FEET  PER  MINUTE 

Stroke  in 
Inches. 


s 


.00  co  oo 

)  O  X*.  to 

1  00  -4  O 


.  *-  O  00  Oi  .«>.  OO  tG  O  «O  00        00 
i  oo  O  •<>  O<iOJ  O -^  00  O  I    C^ 


58l  8 


)<l  OS  V  yi  i*^  >U  >U  ; 
'  t*  O  OS  M  00  >U  O  < 

>  C  O  O  O  O  O  C  i 


>  o  o  o  o  ^ 


IS3SSI  £ 


4w  Ci 


^^C^ 


;5§8l.i 


l£i_i-ii— _M 

"to~to  to  -» i-n 


liil  i 


rf^.  C5  OiiOOOO»*i*OtC4X.O 


PllfSillilSSjggStSSfeSg! 

_o  i—1  o_o  ojo  oa  o  o  CT>  oo  o  — ?  oo-o  <i.  w  oo  o  oo  -^  m  i 

"iC  CO.'ltC  K>"tO  >-*"—  M  t-i  i-i' i^Ti- i-i  "         "  ~ 

~co  co"oo  tototcrc>-'M>— h^i-n-ii-i 


^§88g8S: 


!£3    SS 

)<JO»  I    O» 


^  O  O  O  O  ^C  Oi  O  O  O5  OC'  O  Ci  00  O  O  ' 

o^Ooo^>o;ooo5>-'C5--i£So-:b< 


ADVERTISEMENTS. 


*j£ot3£C:<3 

«f  |  S,  5  K-  5  »  I  mm 

"1    £          C   (D        «J    3  f"™1  *••> 

SJBpBBP^S  p-n  g 

T     CO  IT"  ~     —  •••  PHHI 

W3    O  P^  >^^/  O  ^PV  *r  _^t 

mifiB  »*  s  iiii  a 

05    O    (t    2    S    O    &1  ^B'-R*1 

••    09  •   p<  i  R)  n  ®  i 


ADVERTISEMENTS. 


GARDNER  T.  VOORHEES,  S.  B 

Refrigerating 


engineer 


OPINIONS,  ESTIMATES,  PLANS,  ETC., 

FOR 

Refrigerating^Ice  Plants 


INDICATOR  CARDS 
WORKED  UP,  ETC. 


41  RICHMOND  STREET 
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works  WET  steam  or  BOILER  foams, 
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"BOYLE" 

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BUILT  BY  THE 


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120  AND  122  LIBERTY  ST.,  NEW  YORK 

Practical 
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A  practical,  common  sense  treatise 
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Machinery  and  Apparatus  :  :  :  : 


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Cable  A 


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4  times  as  many  as 
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